* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default [not found] ` <<83zjp5h33w.fsf@gnu.org> @ 2013-11-15 21:21 ` Drew Adams 0 siblings, 0 replies; 39+ messages in thread From: Drew Adams @ 2013-11-15 21:21 UTC (permalink / raw) To: Eli Zaretskii; +Cc: 15899 > > 1. I meant that the change to the behavior of the region not > > appearing "on top of" other highlighting (except isearch) > > needs to be reverted (undone). > > You cannot revert behavior, only the code. I added "(undone)", to be clear. And no, code is not the only thing that can be reverted. When you revert a buffer using `g', you are reverting behavior/effects, not reverting code. Revert just means to go back to a previous state. > If the new implementation has unwanted side effects, those side > effects need to be fixed by further changes. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ No, that is not the need. The need is to remove the unwanted side effects - sure. But that does not imply keeping the culprit code and then trying to make "further changes" to make things right. That is only one possible approach. It is not _necessary_ to follow that approach -there is no such "need". Another approach is to (1) revert the code changes that brought about the regression and then (2) fix the bug those changes were intended to fix in some other way. That is, assuming there really was a bug to be fixed. Can you say what it was? If so, can you also say why keeping the changes made so far and applying (unknown) "further changes" is the best way to go? > > 4. If it was in fact a bug, it's not clear why the fix for it > > needed to involve changing region highlighting to use an > > overlay. Not clear to me anyway. > > It doesn't have to be clear. I assume you mean that it does not have to be clear to me. Hopefully you agree that it has to be clear to someone. Is it clear to you? If so, do tell, pray. > The fact that region highlighting now uses an overlay is an > implementation detail. No, it is not. Why? Because Emacs _users_ do things with buffer text, and with text properties, and with overlays. These are not simply implementation artifacts. They are first class Emacs thingies that can be and are manipulated by Emacs users. Some users might not care whether some particular highlighting is via a text property or an overlay. Other users might care. Depends on what they are doing. Users interact with Emacs in lots of ways besides interactive use of `emacs -Q' commands and menus. They add text properties, examine them, change them, search their text, change their text,... This is a passably big change for Emacs Users. Emacs has used text property `face' to "implement" region highlighting ever since such highlighting has existed. Why no proposal for such a change? No discussion? > Bug reports should generally remain on the level of behavior, > i.e. requirements, they should not normally go to the > implementation level. What is the _behavioral requirement_ that obliges the use of an overlay for the region? Can you answer that? I've seen nothing so far. Talk about text properties vs overlays is on the user level, as well as the developer level. It is mistaken to think that it is something hidden to users inside some "implementation level". > The implementors should have freedom to implement the > required behavior as they see fit, as long as the results are > reasonable. Sure they should. But just what is the required behavior here? And how relative is that "freedom"? And what is the community of "implementors" that should enjoy this freedom? "The implementors" are not a separate breed from Emacs users. We are in this together. ("The educator himself must be educated." - Theses on Feuerbach) > > My suggestion is to first revert the code change and then > > discuss what the bug is that it was intended to fix. If > > there is really a bug that needs fixing, then let's please > > try to find some other, non-shotgun fix for it. > > Again, please stay on the level of required behavior, and > leave the implementation out of this discussion. Something wrong with discussing implementation among "implementors"? Among users too? Not at all. > As long as there's no evidence that the new implementation ^^^^^^^^^^^ > cannot possibly accommodate the required behavior, the ^^^^^^^^^^^^^^^^^^^^^^^^^^^ > implementation can stay. Setting the bar a bit high, aren't you? Balderdash. As long as there is no evidence that the _old_ implementation "cannot possibly accommodate" other changes that fix the bug, the old implementation can stay. You are being simplistic here. The new implementation is not the One Tried & True that cannot be questioned. It is not arguments against the new implementation that need to be proved beyond a reasonable doubt. That's backwards. What should be demonstrated is why we should choose a new region implementation. This change has not even been released yet - why on Earth put up a wall of "as long as there is no evidence that it cannot possibly accommodate"? As if it were enshrined in unquestionable tradition. It's bad enough to defend a longstanding and proven status quo dogmatically. It's downright ridiculous to do so for a change that is only a few days old and has not yet seen the Light of User Day. Is there even any "evidence" that there was a bug to be fixed? Again, can you say what the bug is, clearly and not referring to implementation? IOW: This is the _requirement_, in terms of behavior: _____ And this is why it is better to fix the remaining problems caused by the recent "fix" than it is to start over with a different fix: _______ ^ permalink raw reply [flat|nested] 39+ messages in thread
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* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default [not found] ` <<83k3g8gug7.fsf@gnu.org> @ 2013-11-16 17:47 ` Drew Adams 0 siblings, 0 replies; 39+ messages in thread From: Drew Adams @ 2013-11-16 17:47 UTC (permalink / raw) To: Eli Zaretskii; +Cc: 15899, jarekczek > > 2. Previously, region highlighting used the `face' text property. > > No, region never used any text properties. There was a 'region' > face, yes, but no text property. Instead, the display engine had > special code for displaying the active region in the 'region' face. You are right about that, Eli. I was quite mistaken about it. Funny (embarrassing), I could have sworn that I had seen face `region' listed as a text property in `C-u C-x =', but I must not have. And yes, I should have double-checked that. Thank you for the correction. And that changes what I said about moving `region' to an overlay taking some text-property behavior away from Lisp users. With that information, I now see no downside (so far) to moving face `region' to an overlay. We just need to get the overlay (by default) to appear to be on top of most other overlays (with isearch as an exception). ^ permalink raw reply [flat|nested] 39+ messages in thread
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* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default [not found] ` <<8338mxipix.fsf@gnu.org> @ 2013-11-15 17:14 ` Drew Adams 2013-11-15 19:33 ` Eli Zaretskii 0 siblings, 1 reply; 39+ messages in thread From: Drew Adams @ 2013-11-15 17:14 UTC (permalink / raw) To: Eli Zaretskii; +Cc: 15899 > > This change should be reverted as soon as possible. > > It needs not be reverted, I think. We just need to make the > priority of the region overlay higher than any other overlay. 1. I meant that the change to the behavior of the region not appearing "on top of" other highlighting (except isearch) needs to be reverted (undone). IOW, bug #15899 is a regression. It is the behavior that needs to be fixed, regardless of how that is done. 2. Region highlighting should *not* be higher priority than all other overlays. It should not be higher than isearch highlighting, for instance. There might be other exceptions too; dunno. See my previous mail. 3. It's not clear that the reported "bug" was in fact a bug, rather than the intended Emacs behavior. Or if it was, it is not clear just what the bug was. If it was thought to be a bug that other highlighting was in some cases overruled by region highlighting, then that was not, IMO, a bug. 4. If it was in fact a bug, it's not clear why the fix for it needed to involve changing region highlighting to use an overlay. Not clear to me anyway. My suggestion is to first revert the code change and then discuss what the bug is that it was intended to fix. If there is really a bug that needs fixing, then let's please try to find some other, non-shotgun fix for it. There should be no need to change the longstanding behavior of the Emacs region just because someone's highlighting does not show through. ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-15 17:14 ` Drew Adams @ 2013-11-15 19:33 ` Eli Zaretskii 0 siblings, 0 replies; 39+ messages in thread From: Eli Zaretskii @ 2013-11-15 19:33 UTC (permalink / raw) To: Drew Adams; +Cc: 15899 > Date: Fri, 15 Nov 2013 09:14:37 -0800 (PST) > From: Drew Adams <drew.adams@oracle.com> > Cc: monnier@iro.umontreal.ca, 15899@debbugs.gnu.org > > > > This change should be reverted as soon as possible. > > > > It needs not be reverted, I think. We just need to make the > > priority of the region overlay higher than any other overlay. > > 1. I meant that the change to the behavior of the region not > appearing "on top of" other highlighting (except isearch) needs > to be reverted (undone). You cannot revert behavior, only the code. If the new implementation has unwanted side effects, those side effects need to be fixed by further changes. > 2. Region highlighting should *not* be higher priority than > all other overlays. It should not be higher than isearch > highlighting, for instance. There might be other exceptions > too; dunno. See my previous mail. I don't disagree. If there are other overlays that should show through the region, they should have higher priority. > 4. If it was in fact a bug, it's not clear why the fix for it > needed to involve changing region highlighting to use an > overlay. Not clear to me anyway. It doesn't have to be clear. The fact that region highlighting now uses an overlay is an implementation detail. Bug reports should generally remain on the level of behavior, i.e. requirements, they should not normally go to the implementation level. The implementors should have freedom to implement the required behavior as they see fit, as long as the results are reasonable. > My suggestion is to first revert the code change and then > discuss what the bug is that it was intended to fix. If > there is really a bug that needs fixing, then let's please > try to find some other, non-shotgun fix for it. Again, please stay on the level of required behavior, and leave the implementation out of this discussion. As long as there's no evidence that the new implementation cannot possibly accommodate the required behavior, the implementation can stay. > There should be no need to change the longstanding behavior > of the Emacs region just because someone's highlighting does > not show through. Agreed. ^ permalink raw reply [flat|nested] 39+ messages in thread
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* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default [not found] ` <<83bo1liv80.fsf@gnu.org> @ 2013-11-15 15:55 ` Drew Adams 2013-11-15 16:43 ` Eli Zaretskii 0 siblings, 1 reply; 39+ messages in thread From: Drew Adams @ 2013-11-15 15:55 UTC (permalink / raw) To: Eli Zaretskii, Stefan Monnier; +Cc: 15899 > Isn't it confusing that the region highlighting is non-contiguous > when an overlay is in its middle? Yes. And when a `face' or other display-related text property is in its middle. Or is at either end. Or extends across the whole region (which includes when the region is in the middle of a stretch of highlighting). I know from experience with the new (and old) behavior. Such situations are visually confusing to users. And they can complicate operating on text properties and, more generally, using text properties and overlays. This change should be reverted as soon as possible. It is a candidate for "What WERE they thinking?" At the very least, make such behavior optional for users (and certainly not the default). There are thousands of real bugs reported, many of them still unresponded to. There is no reason to spend time "fixing" non-bugs such as this. This should have gotten only a polite "This is by design", perhaps followed by an explanation of why the design (in Emacs and everywhere else!) is thus. ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-15 15:55 ` Drew Adams @ 2013-11-15 16:43 ` Eli Zaretskii 0 siblings, 0 replies; 39+ messages in thread From: Eli Zaretskii @ 2013-11-15 16:43 UTC (permalink / raw) To: Drew Adams; +Cc: 15899 > Date: Fri, 15 Nov 2013 07:55:27 -0800 (PST) > From: Drew Adams <drew.adams@oracle.com> > Cc: 15899@debbugs.gnu.org > > > Isn't it confusing that the region highlighting is non-contiguous > > when an overlay is in its middle? > > Yes. And when a `face' or other display-related text property is > in its middle. Or is at either end. Or extends across the whole > region (which includes when the region is in the middle of a > stretch of highlighting). I know from experience with the new > (and old) behavior. > > Such situations are visually confusing to users. And they can > complicate operating on text properties and, more generally, > using text properties and overlays. > > This change should be reverted as soon as possible. It needs not be reverted, I think. We just need to make the priority of the region overlay higher than any other overlay. ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default @ 2013-11-14 22:57 Drew Adams 2013-11-15 7:41 ` Eli Zaretskii 2013-11-15 16:53 ` Barry OReilly 0 siblings, 2 replies; 39+ messages in thread From: Drew Adams @ 2013-11-14 22:57 UTC (permalink / raw) To: 15899 In Emacs 24.3, if you highlight some text with an overlay, without specifying any priority for the overlay, that overlay will be lower priority than the `region' face overlay that is used to select text for the region. In this build, the region overlay is of lower priority, so the other overlay hides the region overlay. To test, create an overlay without specifying any priority. E.g. evaluate this in buffer *scratch* from emacs -Q. (text-mode) ; No font lock interference. (setq overlay (make-overlay 20 40)) (overlay-put overlay 'face 'highlight) Then select text in the first line, from before char 20 to after char 40. The highlighting from 20 to 40 shows, instead of the region. Do the same thing in Emacs 24.3 - no bug there. Dunno when the regression started. In GNU Emacs 24.3.50.1 (i686-pc-mingw32) of 2013-11-12 on LEG570 Windowing system distributor `Microsoft Corp.', version 6.1.7601 Configured using: `configure --enable-checking 'CFLAGS=-O0 -g3' CPPFLAGS=-DGLYPH_DEBUG=1' ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-14 22:57 Drew Adams @ 2013-11-15 7:41 ` Eli Zaretskii 2013-11-15 13:54 ` Stefan Monnier 2013-11-15 16:53 ` Barry OReilly 1 sibling, 1 reply; 39+ messages in thread From: Eli Zaretskii @ 2013-11-15 7:41 UTC (permalink / raw) To: Drew Adams; +Cc: 15899 > Date: Thu, 14 Nov 2013 14:57:14 -0800 (PST) > From: Drew Adams <drew.adams@oracle.com> > > In Emacs 24.3, if you highlight some text with an overlay, without > specifying any priority for the overlay, that overlay will be lower > priority than the `region' face overlay that is used to select text for > the region. > > In this build, the region overlay is of lower priority, so the other > overlay hides the region overlay. In Emacs 24.3, the region highlight was not done by an overlay, but by special code in C. Now it is an overlay, so the issue of priority creeps in. > Do the same thing in Emacs 24.3 - no bug there. Dunno when the > regression started. It started when Stefan made the region use an overlay. ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-15 7:41 ` Eli Zaretskii @ 2013-11-15 13:54 ` Stefan Monnier 2013-11-15 14:40 ` Eli Zaretskii 2013-11-15 15:51 ` Drew Adams 0 siblings, 2 replies; 39+ messages in thread From: Stefan Monnier @ 2013-11-15 13:54 UTC (permalink / raw) To: Eli Zaretskii; +Cc: 15899 > In Emacs 24.3, the region highlight was not done by an overlay, but by > special code in C. Now it is an overlay, so the issue of priority > creeps in. Indeed. OTOH, I'm not convinced it's a bug, since this "bug" was also the fix for another bug. It's a change, there's no doubt about that. Whether it's better or worse is not so clear. Stefan ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-15 13:54 ` Stefan Monnier @ 2013-11-15 14:40 ` Eli Zaretskii 2013-11-15 15:32 ` Dmitry Gutov 2013-11-16 1:25 ` Stefan Monnier 2013-11-15 15:51 ` Drew Adams 1 sibling, 2 replies; 39+ messages in thread From: Eli Zaretskii @ 2013-11-15 14:40 UTC (permalink / raw) To: Stefan Monnier; +Cc: 15899 > From: Stefan Monnier <monnier@iro.umontreal.ca> > Cc: Drew Adams <drew.adams@oracle.com>, 15899@debbugs.gnu.org > Date: Fri, 15 Nov 2013 08:54:15 -0500 > > I'm not convinced it's a bug, since this "bug" was also the fix for > another bug. Was that other bug also about priorities of faces? > It's a change, there's no doubt about that. Whether it's better or > worse is not so clear. Isn't it confusing that the region highlighting is non-contiguous when an overlay is in its middle? What are the downsides of setting the region overlay's priority to most-positive-fixnum? ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-15 14:40 ` Eli Zaretskii @ 2013-11-15 15:32 ` Dmitry Gutov 2013-11-15 16:40 ` Eli Zaretskii 2013-11-16 1:25 ` Stefan Monnier 1 sibling, 1 reply; 39+ messages in thread From: Dmitry Gutov @ 2013-11-15 15:32 UTC (permalink / raw) To: Eli Zaretskii; +Cc: 15899 Eli Zaretskii <eliz@gnu.org> writes: >> From: Stefan Monnier <monnier@iro.umontreal.ca> >> Cc: Drew Adams <drew.adams@oracle.com>, 15899@debbugs.gnu.org >> Date: Fri, 15 Nov 2013 08:54:15 -0500 >> >> I'm not convinced it's a bug, since this "bug" was also the fix for >> another bug. > > Was that other bug also about priorities of faces? Yes. http://debbugs.gnu.org/cgi/bugreport.cgi?bug=15618 ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-15 15:32 ` Dmitry Gutov @ 2013-11-15 16:40 ` Eli Zaretskii 2013-11-15 22:35 ` Dmitry Gutov 0 siblings, 1 reply; 39+ messages in thread From: Eli Zaretskii @ 2013-11-15 16:40 UTC (permalink / raw) To: Dmitry Gutov; +Cc: 15899 > From: Dmitry Gutov <dgutov@yandex.ru> > Cc: Stefan Monnier <monnier@iro.umontreal.ca>, 15899@debbugs.gnu.org > Date: Fri, 15 Nov 2013 17:32:07 +0200 > > Eli Zaretskii <eliz@gnu.org> writes: > > >> From: Stefan Monnier <monnier@iro.umontreal.ca> > >> Cc: Drew Adams <drew.adams@oracle.com>, 15899@debbugs.gnu.org > >> Date: Fri, 15 Nov 2013 08:54:15 -0500 > >> > >> I'm not convinced it's a bug, since this "bug" was also the fix for > >> another bug. > > > > Was that other bug also about priorities of faces? > > Yes. http://debbugs.gnu.org/cgi/bugreport.cgi?bug=15618 But since the region is now an overlay, the inconsistency will be gone, right? ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-15 16:40 ` Eli Zaretskii @ 2013-11-15 22:35 ` Dmitry Gutov 2013-11-16 8:49 ` Eli Zaretskii 0 siblings, 1 reply; 39+ messages in thread From: Dmitry Gutov @ 2013-11-15 22:35 UTC (permalink / raw) To: Eli Zaretskii; +Cc: 15899 On 15.11.2013 18:40, Eli Zaretskii wrote: >>>> I'm not convinced it's a bug, since this "bug" was also the fix for >>>> another bug. >>> >>> Was that other bug also about priorities of faces? >> >> Yes. http://debbugs.gnu.org/cgi/bugreport.cgi?bug=15618 > > But since the region is now an overlay, the inconsistency will be > gone, right? Yes, but if the region overlay will have priority infinity, the inconsistency will "be gone" in the opposite way from how 15618 was resolved. Which will make the related feature of `easy-kill' much harder (maybe impossible) to implement. If the region overlay will have a high but finite and documented priority, that would be much better. ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-15 22:35 ` Dmitry Gutov @ 2013-11-16 8:49 ` Eli Zaretskii 2013-11-16 9:51 ` Jarek Czekalski 2013-11-16 10:25 ` Dmitry Gutov 0 siblings, 2 replies; 39+ messages in thread From: Eli Zaretskii @ 2013-11-16 8:49 UTC (permalink / raw) To: Dmitry Gutov; +Cc: 15899 > Date: Sat, 16 Nov 2013 00:35:25 +0200 > From: Dmitry Gutov <dgutov@yandex.ru> > CC: monnier@iro.umontreal.ca, 15899@debbugs.gnu.org > > On 15.11.2013 18:40, Eli Zaretskii wrote: > >>>> I'm not convinced it's a bug, since this "bug" was also the fix for > >>>> another bug. > >>> > >>> Was that other bug also about priorities of faces? > >> > >> Yes. http://debbugs.gnu.org/cgi/bugreport.cgi?bug=15618 > > > > But since the region is now an overlay, the inconsistency will be > > gone, right? > > Yes, but if the region overlay will have priority infinity, the > inconsistency will "be gone" in the opposite way from how 15618 was > resolved. But the behavior will still be consistent. And complaint about inconsistency is how I read that bug report. It even asks "which is the right behavior?", implying that having it consistent either way would be OK. > Which will make the related feature of `easy-kill' much harder (maybe > impossible) to implement. Can you tell more about this feature, and why it cares to be "more equal" than the region? (Sorry, I don't have time to read the source or try it.) Why is it important for easy-kill overlay to make region highlighting invisible? > If the region overlay will have a high but finite and documented > priority, that would be much better. Which will start an "overlay priority arms race", something I loathe. ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-16 8:49 ` Eli Zaretskii @ 2013-11-16 9:51 ` Jarek Czekalski 2013-11-16 10:42 ` Eli Zaretskii [not found] ` <<83ppq0hbln.fsf@gnu.org> 2013-11-16 10:25 ` Dmitry Gutov 1 sibling, 2 replies; 39+ messages in thread From: Jarek Czekalski @ 2013-11-16 9:51 UTC (permalink / raw) To: 15899 W dniu 2013-11-16 09:49, Eli Zaretskii pisze: >> If the region overlay will have a high but finite and documented >> priority, that would be much better. > Which will start an "overlay priority arms race", something I loathe. From this point of view editors like Notepad are best. No races, no possibility of user or package interfering with application author's vision. But we are in Emacs. This should mean freedom to users. If a user wants to have a higher priority, why would you forbid him to do so? I can't imagine an example where infinite priority is better than a high value. Could you help with that? I guess examples of malicious users or those who don't read docs should not count. Jarek ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-16 9:51 ` Jarek Czekalski @ 2013-11-16 10:42 ` Eli Zaretskii 2013-11-16 14:43 ` Jarek Czekalski [not found] ` <<83ppq0hbln.fsf@gnu.org> 1 sibling, 1 reply; 39+ messages in thread From: Eli Zaretskii @ 2013-11-16 10:42 UTC (permalink / raw) To: Jarek Czekalski; +Cc: 15899 > Date: Sat, 16 Nov 2013 10:51:55 +0100 > From: Jarek Czekalski <jarekczek@poczta.onet.pl> > > W dniu 2013-11-16 09:49, Eli Zaretskii pisze: > >> If the region overlay will have a high but finite and documented > >> priority, that would be much better. > > Which will start an "overlay priority arms race", something I loathe. > > From this point of view editors like Notepad are best. No races, no > possibility of user or package interfering with application author's > vision. But we are in Emacs. This should mean freedom to users. If a > user wants to have a higher priority, why would you forbid him to do so? Every freedom must have its limits. "Your freedom to swing fists ends where my nose begins." (Yes, I know I'm lecturing, but so did you.) More to the point: Previously, Emacs users did not have the freedom to overrule the region highlighting with an overlay face. Many generations of Emacs users lived with that limitation and never complained about that, at least not seriously enough to make this an issue. Keeping the priority of the region overlay at infinity just preserves previous behavior. So I think we should turn the table and ask why would a user need to have this freedom now, and only give that freedom if the cause justifies it. > I can't imagine an example where infinite priority is better than a high > value. Could you help with that? It avoids the problem of priority race. With an infinite priority, we can be sure the region highlighting will always be visible, come what may. > I guess examples of malicious users or those who don't read docs > should not count. No, but unintended consequences of actions by unsuspecting users should. In a complex system, unintended consequences are always a greater danger than malicious intent. IOW, keeping the region priority above everything makes sure we won't have another series of bug reports in the near future asking why this or that feature makes region invisible. ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-16 10:42 ` Eli Zaretskii @ 2013-11-16 14:43 ` Jarek Czekalski 0 siblings, 0 replies; 39+ messages in thread From: Jarek Czekalski @ 2013-11-16 14:43 UTC (permalink / raw) To: 15899 W dniu 2013-11-16 11:42, Eli Zaretskii pisze: > Every freedom must have its limits. "Your freedom to swing fists ends > where my nose begins." (Yes, I know I'm lecturing, but so did you.) Sorry if you didn't like my tone. I tried to make a general point and justify it well. On the other hand, I don't mind lecturing like yours, if that's what we call lecturing here. > So I think we should turn the table and ask why would a user need to > have this freedom now, and only give that freedom if the cause > justifies it. Good point. I would do it just for the sake of flexibility, which Emacs should be proud of. We may not predict in what way people will want to user overlays. And some of them may be silently disappointed if flexibility of overlays is not sufficient. They even won't complain about it, so we may never hear such a request. But if flexibility is achieved, there may be silent happy users. That's a benefit. Introducing a new feature needs considering pros and cons. Personally I don't see enough cons. Dmitri's answer presents ways to deal with potential problems. Good documentation would be the most important weapon. Something like: "It is strongly suggested not to specify a priority higher than ..., because it will cause problems with displaying selection boundaries." An example of such need just came to my mind. A temporary overlay which highlights for a second the words spoken by a user through a microphone. So if I were to decide, I would say: freedom and flexibility! Sorry again for lecturing. And being pathetic too :) Jarek ^ permalink raw reply [flat|nested] 39+ messages in thread
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* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default [not found] ` <<83ppq0hbln.fsf@gnu.org> @ 2013-11-16 16:23 ` Drew Adams 2013-11-16 16:52 ` Eli Zaretskii 2013-11-16 22:01 ` Stefan Monnier 0 siblings, 2 replies; 39+ messages in thread From: Drew Adams @ 2013-11-16 16:23 UTC (permalink / raw) To: Eli Zaretskii, Jarek Czekalski; +Cc: 15899 > Previously, Emacs users did not have the freedom to > overrule the region highlighting with an overlay face. Many > generations of Emacs users lived with that limitation and never > complained about that, at least not seriously enough to make this an > issue. Keeping the priority of the region overlay at infinity just > preserves previous behavior. No, it does not preserve previous behavior. 1. Previously, isearch highlighting took priority over region highlighting. Isearch highlighting has a large, finite value. 2. Previously, region highlighting used the `face' text property. 3rd-party code and user code and interactions that manipulate text properties will no longer work. Yes, using an overlay for the region brings other possibilities. But it takes away certain possibilities, as well (#2). > > I can't imagine an example where infinite priority is better than > > a high value. Could you help with that? > > It avoids the problem of priority race. If you declare a winner ahead of time then there is no race. Big deal. Isearch needs (by default, at least) to win out over region. And why not others as well, depending on need? Why foreclose the possibility? Sure, if someone wants to fiddle with priorites then there is always the potential for escalation spiraling round. That's life with Lisp. > With an infinite priority, we can be sure the region highlighting > will always be visible, come what may. Which might not always be what someone wants. I'm all for region appearing on top, by default, as I've already argued in detail. Users need to know what they've selected. But that does not mean that someone should be prevented from doing things otherwise. > IOW, keeping the region priority above everything makes sure we > won't have another series of bug reports in the near future asking > why this or that feature makes region invisible. That's just an argument for the default behavior. "_Keeping_ the priority above everything else" is wrong. _Setting_ it above everything else (with exceptions such as isearch) by default is right. ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-16 16:23 ` Drew Adams @ 2013-11-16 16:52 ` Eli Zaretskii 2013-11-16 22:01 ` Stefan Monnier 1 sibling, 0 replies; 39+ messages in thread From: Eli Zaretskii @ 2013-11-16 16:52 UTC (permalink / raw) To: Drew Adams; +Cc: 15899, jarekczek > Date: Sat, 16 Nov 2013 08:23:35 -0800 (PST) > From: Drew Adams <drew.adams@oracle.com> > Cc: 15899@debbugs.gnu.org > > 2. Previously, region highlighting used the `face' text property. No, region never used any text properties. There was a 'region' face, yes, but no text property. Instead, the display engine had special code for displaying the active region in the 'region' face. ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-16 16:23 ` Drew Adams 2013-11-16 16:52 ` Eli Zaretskii @ 2013-11-16 22:01 ` Stefan Monnier 2013-11-16 22:42 ` Drew Adams 1 sibling, 1 reply; 39+ messages in thread From: Stefan Monnier @ 2013-11-16 22:01 UTC (permalink / raw) To: Drew Adams; +Cc: 15899, Jarek Czekalski > 2. Previously, region highlighting used the `face' text property. > 3rd-party code and user code and interactions that manipulate text > properties will no longer work. Obviously you don't know what you're talking about. Stfean ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-16 22:01 ` Stefan Monnier @ 2013-11-16 22:42 ` Drew Adams 0 siblings, 0 replies; 39+ messages in thread From: Drew Adams @ 2013-11-16 22:42 UTC (permalink / raw) To: Stefan Monnier; +Cc: 15899, Jarek Czekalski > > 2. Previously, region highlighting used the `face' text property. > > 3rd-party code and user code and interactions that manipulate text > > properties will no longer work. > > Obviously you don't know what you're talking about. Feel better now, Stefan? I already said several hours ago, after Eli pointed it out, that I was mistaken in thinking that face `region' was applied as a text property. I was (mistakenly) convinced that I had seen it listed in `C-u C-x =' output as such. Mea culpa (again). At least I know enough to guess that selection highlighting should, at the very least by default, visibly cover the entire selection. That's a no-brainer, in my book. But then, I don't know what I'm talking about. ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-16 8:49 ` Eli Zaretskii 2013-11-16 9:51 ` Jarek Czekalski @ 2013-11-16 10:25 ` Dmitry Gutov 2013-11-16 11:24 ` Eli Zaretskii ` (2 more replies) 1 sibling, 3 replies; 39+ messages in thread From: Dmitry Gutov @ 2013-11-16 10:25 UTC (permalink / raw) To: Eli Zaretskii; +Cc: 15899 On 16.11.2013 10:49, Eli Zaretskii wrote: >> Yes, but if the region overlay will have priority infinity, the >> inconsistency will "be gone" in the opposite way from how 15618 was >> resolved. > > But the behavior will still be consistent. And complaint about > inconsistency is how I read that bug report. It even asks "which is > the right behavior?", implying that having it consistent either way > would be OK. The bug report was what is was, but `easy-kill' depends on region highlighting working in a certain way. >> Which will make the related feature of `easy-kill' much harder (maybe >> impossible) to implement. > > Can you tell more about this feature, and why it cares to be "more > equal" than the region? (Sorry, I don't have time to read the source > or try it.) Why is it important for easy-kill overlay to make region > highlighting invisible? It has a command `easy-mark' which selects some unit of text around point. And it uses a dedicated overlay to mark the place where point was before the command was called, in color. So that overlay needs to have higher priority than region. No need to make region highlighting invisible. >> If the region overlay will have a high but finite and documented >> priority, that would be much better. > > Which will start an "overlay priority arms race", something I loathe. I don't think so. The region overlay priority won't change, even if people decide to shoot themselves in the foot and raise priorities of overlays inappropriately. ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-16 10:25 ` Dmitry Gutov @ 2013-11-16 11:24 ` Eli Zaretskii 2013-11-16 13:49 ` Dmitry Gutov 2013-11-16 16:20 ` Drew Adams [not found] ` <<83ob5kh9nb.fsf@gnu.org> 2 siblings, 1 reply; 39+ messages in thread From: Eli Zaretskii @ 2013-11-16 11:24 UTC (permalink / raw) To: Dmitry Gutov; +Cc: 15899 > Date: Sat, 16 Nov 2013 12:25:36 +0200 > From: Dmitry Gutov <dgutov@yandex.ru> > CC: monnier@iro.umontreal.ca, 15899@debbugs.gnu.org > > `easy-kill' depends on region highlighting working in a certain way. What way is that? Before region highlighting was reimplemented as an overlay, it had a fixed "priority" that couldn't be controlled or worked around. So what exactly did easy-kill expect from that behavior? > It has a command `easy-mark' which selects some unit of text around > point. And it uses a dedicated overlay to mark the place where point was > before the command was called, in color. But the region always has point on one of its ends, so both the places where point was and where it is are clearly visible when the region is active. So why is there a need for the easy-mark to be visible in that situation (which is transient and therefore short-lived)? > So that overlay needs to have higher priority than region. No need to > make region highlighting invisible. The part of the region that overlaps the easy-mark overlay will not be visible, if the region's priority is lower. Or did you mean something else? > >> If the region overlay will have a high but finite and documented > >> priority, that would be much better. > > > > Which will start an "overlay priority arms race", something I loathe. > > I don't think so. The region overlay priority won't change, even if > people decide to shoot themselves in the foot and raise priorities of > overlays inappropriately. That's not the race I had in mind. What I had in mind was users complaining about their favorite overlay-based features being obscured by the region, lobbying the maintainers to increase the priorities of those overlays above the region (and possibly also above the easy-mark overlay), or increase the priority of the region overlay; then other users complaining about the effects of that, and so on and so forth ad nauseam. How can you even assume that the "region overlay priority won't change", given the possibility and enough pressure from users? Once out of the bottle, this genie cannot be easily put back. ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-16 11:24 ` Eli Zaretskii @ 2013-11-16 13:49 ` Dmitry Gutov 2013-11-16 16:30 ` Drew Adams 0 siblings, 1 reply; 39+ messages in thread From: Dmitry Gutov @ 2013-11-16 13:49 UTC (permalink / raw) To: Eli Zaretskii; +Cc: 15899 On 16.11.2013 13:24, Eli Zaretskii wrote: > What way is that? Before region highlighting was reimplemented as an > overlay, it had a fixed "priority" that couldn't be controlled or > worked around. So what exactly did easy-kill expect from that > behavior? That behavior was broken on Leo Liu's system (don't know how) and on mine too (with some themes only). See https://github.com/leoliu/easy-kill/issues/3 for more details. > But the region always has point on one of its ends, so both the places > where point was and where it is are clearly visible when the region is > active. In many times point wasn't at any of region ends. That's how `easy-mark' works, it selects some unit of text *around* the point. > So why is there a need for the easy-mark to be visible in > that situation (which is transient and therefore short-lived)? Just for user information. Looks kinda nice. > The part of the region that overlaps the easy-mark overlay will not be > visible, if the region's priority is lower. That just means that easy-mark will need to set its priority higher than the *documented* region priority. > That's not the race I had in mind. What I had in mind was users > complaining about their favorite overlay-based features being obscured > by the region, lobbying the maintainers to increase the priorities of > those overlays above the region (and possibly also above the easy-mark > overlay), or increase the priority of the region overlay; then other > users complaining about the effects of that, and so on and so forth ad > nauseam. This will have to be solved on a package-by-package basis, like every contentious feature. One user complaint: change the priority of a package-specific overlay. More complaints to change it in different directions: add a user option that will set the priority that overlay. > How can you even assume that the "region overlay priority > won't change", given the possibility and enough pressure from users? > Once out of the bottle, this genie cannot be easily put back. Region priority will have to be set once (to 100, or something), documented, and then never changed again. Any changes will have to be made to other overlays' priorities. ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-16 13:49 ` Dmitry Gutov @ 2013-11-16 16:30 ` Drew Adams 0 siblings, 0 replies; 39+ messages in thread From: Drew Adams @ 2013-11-16 16:30 UTC (permalink / raw) To: Dmitry Gutov, Eli Zaretskii; +Cc: 15899 > > ... users complaining about the effects of that, and so on and > > so forth ad nauseam. > > This will have to be solved on a package-by-package basis, like > every contentious feature. One user complaint: change the priority > of a package-specific overlay. More complaints to change it in > different directions: add a user option that will set the priority > that overlay. Yes. > > How can you even assume that the "region overlay priority > > won't change", given the possibility and enough pressure from > > users? Once out of the bottle, this genie cannot be easily put back. > > Region priority will have to be set once (to 100, or something), > documented, and then never changed again. Any changes will have to > be made to other overlays' priorities. Yes. But users will also be able to change the priority of the region overlay. You are both right: The overlay genie is a genie, and it will definitely be out of the bottle (Eli). It is only the default region overlay that needs to be defined (well). Users changing that or other priorities can do good and or harm. Emacs Dev need not change the default priority of the region (or any other) overlay, unless it thinks that is appropriate (Dmitry). Think isearch overlay priorities. Have they ever changed? Has there been a deluge of user whining that they need to be changed? ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-16 10:25 ` Dmitry Gutov 2013-11-16 11:24 ` Eli Zaretskii @ 2013-11-16 16:20 ` Drew Adams [not found] ` <<83ob5kh9nb.fsf@gnu.org> 2 siblings, 0 replies; 39+ messages in thread From: Drew Adams @ 2013-11-16 16:20 UTC (permalink / raw) To: Dmitry Gutov, Eli Zaretskii; +Cc: 15899 > It has a command `easy-mark' which selects some unit of text around > point. And it uses a dedicated overlay to mark the place where point > was before the command was called, in color. > > So that overlay needs to have higher priority than region. No need > to make region highlighting invisible. Similarly, the isearch overlays should have higher priority than any region overlay. (And yes, I agree with you that users should of course be able to change priorities as they see fit.) If region highlighting is to use an overlay, then its default priority should be higher than most predefined (i.e., emacs -Q) overlays, but lower than the isearch priorities. ^ permalink raw reply [flat|nested] 39+ messages in thread
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* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default [not found] ` <<83ob5kh9nb.fsf@gnu.org> @ 2013-11-16 16:24 ` Drew Adams 0 siblings, 0 replies; 39+ messages in thread From: Drew Adams @ 2013-11-16 16:24 UTC (permalink / raw) To: Eli Zaretskii, Dmitry Gutov; +Cc: 15899 > > I don't think so. The region overlay priority won't change, even > > if people decide to shoot themselves in the foot and raise > > priorities of overlays inappropriately. > > That's not the race I had in mind. What I had in mind was users > complaining about their favorite overlay-based features being > obscured by the region, lobbying the maintainers to increase the > priorities of those overlays above the region (and possibly also > above the easy-mark overlay), or increase the priority of the region > overlay; then other users complaining about the effects of that, > and so on and so forth ad nauseam. How can you even assume that > the "region overlay priority won't change", given the possibility > and enough pressure from users? User complaint escalation is the escalation you fear? That's a new one. Emacs Dev has never had much trouble resisting user complaints to change defaults. And foreclosing such debate is never the solution anyway. Just set the default priority for the region overlay to a value close to but lower than the isearch overlays. If there are future suggestions to tweak default priorities then that will be discussed concretely when it comes up. If users - or you - have good reasons to change default priorities, then those can be adjusted. > Once out of the bottle, this genie cannot be easily put back. Once face `region' is used for an overlay and not a text property, the overlay genie is out of the bottle, yes. New possibilities arrive, and some old possibilities leave. ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-15 14:40 ` Eli Zaretskii 2013-11-15 15:32 ` Dmitry Gutov @ 2013-11-16 1:25 ` Stefan Monnier 2013-11-16 9:06 ` Eli Zaretskii 2014-02-10 4:14 ` Lars Ingebrigtsen 1 sibling, 2 replies; 39+ messages in thread From: Stefan Monnier @ 2013-11-16 1:25 UTC (permalink / raw) To: Eli Zaretskii; +Cc: 15899 > Isn't it confusing that the region highlighting is non-contiguous when > an overlay is in its middle? 1- you need more than "an overlay in its middle": you need this overlay to put a face property that happens to completely cancel the region's own face properties (since the `face' properties of overlapping overlays are merged). 2- I don't think it's particularly confusing, no. Usually the context makes it pretty clear, and if the user is surprised at some point, that surprise will most likely not last very long. So, no, I don't really think it's a bug. > What are the downsides of setting the region overlay's priority to > most-positive-fixnum? I most-positive-fixnum-ly hate overlay priorities. Stefan ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-16 1:25 ` Stefan Monnier @ 2013-11-16 9:06 ` Eli Zaretskii 2013-11-16 17:45 ` Stefan Monnier 2014-02-10 4:14 ` Lars Ingebrigtsen 1 sibling, 1 reply; 39+ messages in thread From: Eli Zaretskii @ 2013-11-16 9:06 UTC (permalink / raw) To: Stefan Monnier; +Cc: 15899 > From: Stefan Monnier <monnier@iro.umontreal.ca> > Cc: drew.adams@oracle.com, 15899@debbugs.gnu.org > Date: Fri, 15 Nov 2013 20:25:46 -0500 > > > Isn't it confusing that the region highlighting is non-contiguous when > > an overlay is in its middle? > > 1- you need more than "an overlay in its middle": you need this overlay > to put a face property that happens to completely cancel the region's > own face properties (since the `face' properties of overlapping > overlays are merged). It's enough for that face to specify a background color, no? That's not uncommon for Emacs features. E.g., try "M-x hl-line-mode RET". > 2- I don't think it's particularly confusing, no. Usually the context > makes it pretty clear, and if the user is surprised at some point, > that surprise will most likely not last very long. Well, a few people just disagreed with you. > > What are the downsides of setting the region overlay's priority to > > most-positive-fixnum? > > I most-positive-fixnum-ly hate overlay priorities. No offense, but I think we can live with that downside ;-) Are there any others? In any case, the moment you reimplemented the region as an overlay, you got us this issue, because it is inherent in the use of overlays, and cannot be escaped. ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-16 9:06 ` Eli Zaretskii @ 2013-11-16 17:45 ` Stefan Monnier 2013-11-16 18:01 ` Drew Adams 2013-11-17 12:25 ` Daniel Colascione 0 siblings, 2 replies; 39+ messages in thread From: Stefan Monnier @ 2013-11-16 17:45 UTC (permalink / raw) To: Eli Zaretskii; +Cc: 15899 >> > Isn't it confusing that the region highlighting is non-contiguous when >> > an overlay is in its middle? >> 1- you need more than "an overlay in its middle": you need this overlay >> to put a face property that happens to completely cancel the region's >> own face properties (since the `face' properties of overlapping >> overlays are merged). > It's enough for that face to specify a background color, no? In some cases, yes, because the region's foreground color is often unnoticeable (e.g. same as default). >> I most-positive-fixnum-ly hate overlay priorities. > No offense, but I think we can live with that downside ;-) The downside is not that I hate it, but the reasons why I hate it: it's as much a source of problems as a solution. `priorities' impose a total ordering, where often there isn't one: in some circumstance one overlay should be on top, in others it's the other way around. The "default priority" at least is able to handle those things sometimes, by making overlays's ordering depending on nesting. > In any case, the moment you reimplemented the region as an overlay, > you got us this issue, because it is inherent in the use of overlays, > and cannot be escaped. It was present before as well. The behavior was different but was also a source of "priority problems". My intuition tells me that if Emacs had use the current system for the last 20 years and had just changed to the "region is always at the very top", people would complain just as much. Stefan ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-16 17:45 ` Stefan Monnier @ 2013-11-16 18:01 ` Drew Adams 2013-11-16 22:00 ` Stefan Monnier 2013-11-17 12:25 ` Daniel Colascione 1 sibling, 1 reply; 39+ messages in thread From: Drew Adams @ 2013-11-16 18:01 UTC (permalink / raw) To: Stefan Monnier, Eli Zaretskii; +Cc: 15899 > > It's enough for that face to specify a background color, no? > > In some cases, yes, because the region's foreground color is > often unnoticeable (e.g. same as default). That's only by default. We should not base too many assumptions on any particular face attributes for face `region'. It is user customizable. Better to plan for it to be like any other face: any attributes at all, at least as much as we can. > >> I most-positive-fixnum-ly hate overlay priorities. > > No offense, but I think we can live with that downside ;-) > > The downside is not that I hate it, but the reasons why I hate > it: it's as much a source of problems as a solution. > `priorities' impose a total ordering, where often there isn't > one: in some circumstance one overlay should be on top, in > others it's the other way around. I don't disagree (and I'm glad that you are giving reasons ;-)). But what is a better approach? A total ordering is black & white, but at least it gives people a degree of control. And at least that control is simple: a total ordering is a simple model. How about giving an example of a problem? And a solution - something that solves that problem and gives users more (not less) control. > The "default priority" at least is able to handle those things > sometimes, by making overlays's ordering depending on nesting. Not sure what that means, and I wish I did understand what you mean by that. Can you give a tiny example to illustrate? > > In any case, the moment you reimplemented the region as an > > overlay, you got us this issue, because it is inherent in > > the use of overlays, and cannot be escaped. > > It was present before as well. The behavior was different > but was also a source of "priority problems". Not clear how so. Can you elaborate? Are you referring to the fact that a user who wants to see some other highlighting (besides isearch) "on top" could not do so? That I can see. If you mean something else then I don't know what it is. > My intuition tells me that if Emacs had use the current system > for the last 20 years and had just changed to the "region is > always at the very top", people would complain just as much. People sometimes complain less when (a) the new behavior is proposed and explained and (b) they have an opportunity to question and discuss it. We are certainly doing that here, now, but this is something that would be more appropriate for emacs-devel, IMO. It would have been better to initiate a discussion and proposal there, pointing to the bug report and outlining what the behavior changes would be. But you've heard this before... ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-16 18:01 ` Drew Adams @ 2013-11-16 22:00 ` Stefan Monnier 0 siblings, 0 replies; 39+ messages in thread From: Stefan Monnier @ 2013-11-16 22:00 UTC (permalink / raw) To: Drew Adams; +Cc: 15899 >> The "default priority" at least is able to handle those things >> sometimes, by making overlays's ordering depending on nesting. > Not sure what that means, and I wish I did understand what you > mean by that. Can you give a tiny example to illustrate? The default ordering between two overlays that have the same priority is that if one of the two overlays is nested in the other it should have higher priority. The idea is to try and avoid having one overlay completely hide another. > Not clear how so. Can you elaborate? Are you referring to > the fact that a user who wants to see some other highlighting > (besides isearch) "on top" could not do so? Exactly. > We are certainly doing that here, now, but this is something > that would be more appropriate for emacs-devel, IMO. It would > have been better to initiate a discussion and proposal there, > pointing to the bug report and outlining what the behavior > changes would be. But you've heard this before... No, the change's purpose was not to fix that bug. It was just a side-effect. The main purpose of the change was to move the region highlighting code out of the redisplay to Elisp. The good news is that if you liked to old behavior you can get it now by writing some Elisp code, whereas in the past you had no such choice. Stefan ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-16 17:45 ` Stefan Monnier 2013-11-16 18:01 ` Drew Adams @ 2013-11-17 12:25 ` Daniel Colascione 2013-11-17 15:42 ` Stefan Monnier 1 sibling, 1 reply; 39+ messages in thread From: Daniel Colascione @ 2013-11-17 12:25 UTC (permalink / raw) To: Stefan Monnier, Eli Zaretskii; +Cc: 15899 On 11/16/2013 09:45 AM, Stefan Monnier wrote: >>>> Isn't it confusing that the region highlighting is non-contiguous when >>>> an overlay is in its middle? >>> 1- you need more than "an overlay in its middle": you need this overlay >>> to put a face property that happens to completely cancel the region's >>> own face properties (since the `face' properties of overlapping >>> overlays are merged). >> It's enough for that face to specify a background color, no? > > In some cases, yes, because the region's foreground color is > often unnoticeable (e.g. same as default). > >>> I most-positive-fixnum-ly hate overlay priorities. >> No offense, but I think we can live with that downside ;-) > > The downside is not that I hate it, but the reasons why I hate it: it's > as much a source of problems as a solution. `priorities' impose a total > ordering, where often there isn't one: in some circumstance one overlay > should be on top, in others it's the other way around. Can you provide an example of an actual case where two overlays should be ordered one way in one context and another in a different context? Nothing comes to mind at the moment. I don't think numeric priorities are as big a social problem as you suspect: in other cases where we use priorities to manage interaction of unrelated modifiers on some base behavior (e.g., NT filter driver altitudes), priorities work well enough and don't lead to arms races. I'd have preferred an ordered list to numeric priorities, but numeric priorities are good enough. ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-17 12:25 ` Daniel Colascione @ 2013-11-17 15:42 ` Stefan Monnier 0 siblings, 0 replies; 39+ messages in thread From: Stefan Monnier @ 2013-11-17 15:42 UTC (permalink / raw) To: Daniel Colascione; +Cc: 15899 > Can you provide an example of an actual case where two overlays should be > ordered one way in one context and another in a different context? Nothing > comes to mind at the moment. No, I admit to not having a concrete case to give you offhand (I do remember that we have bumped into such problems in the past, tho). The issue boils down to the fact that we generally don't want an overlay to hide another. But priorities are not a good way to solve this problem, since the "hiding" depends on the relative position: if an overlay A is nested within another overlay B, then A should be "on top" in order not to be hidden, and if later the relative position of A changes such that B is now nested into A, then B should now be "on top". Sometimes we really do want one overlay to "be on top", including hiding another, and in that case priorities can work OK. > I don't think numeric priorities are as big a social problem as you suspect: Indeed, there's also the general problems of priorities, e.g. where A wants to be on top of B, C wants to be on top of A and B wants to be on top of C. And I agree that in practice these issues aren't all that bad. But overlays have their own additional issues, specific to their nature. Stefan ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-16 1:25 ` Stefan Monnier 2013-11-16 9:06 ` Eli Zaretskii @ 2014-02-10 4:14 ` Lars Ingebrigtsen 1 sibling, 0 replies; 39+ messages in thread From: Lars Ingebrigtsen @ 2014-02-10 4:14 UTC (permalink / raw) To: Stefan Monnier; +Cc: 15899 Stefan Monnier <monnier@iro.umontreal.ca> writes: >> Isn't it confusing that the region highlighting is non-contiguous when >> an overlay is in its middle? > > 1- you need more than "an overlay in its middle": you need this overlay > to put a face property that happens to completely cancel the region's > own face properties (since the `face' properties of overlapping > overlays are merged). > 2- I don't think it's particularly confusing, no. Usually the context > makes it pretty clear, and if the user is surprised at some point, > that surprise will most likely not last very long. > So, no, I don't really think it's a bug. Closing. -- (domestic pets only, the antidote for overdose, milk.) bloggy blog http://lars.ingebrigtsen.no/ ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-15 13:54 ` Stefan Monnier 2013-11-15 14:40 ` Eli Zaretskii @ 2013-11-15 15:51 ` Drew Adams 2013-11-16 1:26 ` Stefan Monnier 1 sibling, 1 reply; 39+ messages in thread From: Drew Adams @ 2013-11-15 15:51 UTC (permalink / raw) To: Stefan Monnier, Eli Zaretskii; +Cc: 15899 > > In Emacs 24.3, the region highlight was not done by an overlay, > > but by special code in C. Now it is an overlay, so the issue > > of priority creeps in. > > Indeed. OTOH, I'm not convinced it's a bug, since this "bug" was > also the fix for another bug. Which other bug? Was that bug there ever since the Emacs region could be highlighted (i.e., several decades old)? Or was that bug introduced recently, as the result of some other change? Maybe there is more than one change that needs to be reverted? Oh, I see that Dmitry has now answered that question: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=15618 Which was NOT a bug, IMO. It should not have been "fixed". The fact that face `region' highlights "on top of" other highlighting is _on purpose_, i.e., by design. Countering that is folly, IMO. What next? Someone wants to see "theme" highlighting on top of Isearch overlays? And someone eagerly jumps in to "fix" that "bug" too? > It's a change, there's no doubt about that. Whether it's better > or worse is not so clear. Are you saying that you think it might not be a bug (regression) to use an overlay rather than a text property? That would be a reasonable question. Or are you suggesting that it might not be a bug that selecting text does not show the selection face throughout the selection? The latter would be unreasonable. When you select text you should always be able to see which text you selected - all of it, even if it is only one character. This should be a no-brainer. The whole point of having a `region' face is to highlight what is in the region. (FWIW, I'm not sure I'm in favor of the change to using an overlay from using a text property either, but that is not what this bug report is about. Using the region to select text, and then replacing face `region' text property with another face or another text property, or otherwise making use of the property, can be useful. Sure, you can make do without `region' as a text property, but why should you have to? Why did this behavior suddenly need to be changed, after four decades or so of use?) Please: 1. If you keep the use of an overlay, at *least* give users a choice (e.g. a user option) of whether face `region' is to be applied as a text property or used for an overlay. 2. When it is used for an overlay, please make its priority higher than others, with the exception of isearch overlays (yes, there can sometimes be a use for continuing to show the region while isearching). If there are any other exceptions needed to bring the behavior back to pre-regression, those would apply also. (I can't think of any other exceptions, right now). These kinds of changes should first be the subject of proposal and discussion in emacs-devel, and perhaps a user poll. They should not be made willy nilly when fixing a bug. IMHO. ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-15 15:51 ` Drew Adams @ 2013-11-16 1:26 ` Stefan Monnier 2013-11-16 3:47 ` Drew Adams 0 siblings, 1 reply; 39+ messages in thread From: Stefan Monnier @ 2013-11-16 1:26 UTC (permalink / raw) To: Drew Adams; +Cc: 15899 > is _on purpose_, i.e., by design. No, it was the result of the implementation technique, no of design. Stefan ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-16 1:26 ` Stefan Monnier @ 2013-11-16 3:47 ` Drew Adams 0 siblings, 0 replies; 39+ messages in thread From: Drew Adams @ 2013-11-16 3:47 UTC (permalink / raw) To: Stefan Monnier; +Cc: 15899 > > The fact that face `region' highlights "on top of" other > > highlighting is _on purpose_, i.e., by design. > > No, it was the result of the implementation technique, no > of design. You "accidentally" cut off that first line, where I said _what_ was by design. I've put it back, to restore the message honestly. How do you know that Emacs Dev did not _intend_ for the region display to appear "on top of" other highlighting (with the exception of isearch)? I don't believe for a second that this was by accident or just a result of an "implementation technique". Not until you can show some supporting evidence for that claim. Without contrary evidence, I am persuaded that Emacs, like every other app that uses selection, chose this behavior for its _user-level_ effect: The point is to show users just what is selected. There is no better reason to make such a choice. Result of an "implementation technique", indeed! And there were already lots of other UIs that showed selection highlighting, before Emacs added its own. Just as for menus, tooltips, mouse-face highlighting, links, text attributes, and much of the rest of the Emacs UI, these things were developed first outside Emacs and only later (sometimes much later) emulated by and added to Emacs. Emacs got its selection highlighting design from others, not as a result of some Emacs "implementation technique". Users everywhere expect a selection highlight to show them clearly what they've selected. That, and not some unspoken "implementation technique", is the reason that Emacs Dev showed the region face clearly throughout the region selected. Up until this regression, that is. If what is now the behavior remains, then Emacs will be the only UI I'm aware of that does not have selection highlighting override other highlighting in appearance - the only one where _you cannot know what you've selected_ based on highlighting. Can you name another UI that does that? This is really, really silly. Usability out the window - poof. Users will have no idea what they are selecting. Except in lucky cases. And even then they will have to remain unsure, because there is no way to tell whether what they are seeing highlighted as selected is really everything that is selected or just some of it. > Usually the context makes it pretty clear, "Usually" there is no other highlighting of the same text. So what? This usual case is not what the bug is about. > and if the user is surprised at some point, that surprise > will most likely not last very long Wrong. They will need to remain unsure - there is no way to know whether something unhighlighted with face `region' is in fact selected. And even if you were right that user confusion would "most likely not last very long" (based on what?), there is _no reason_ that users have to be confused about selection coverage at all. This-won't-hurt-long is no consolation, because there is no need to inflict pain in the first place. No reason not to show them the region highlighted normally. ^ permalink raw reply [flat|nested] 39+ messages in thread
* bug#15899: 24.3.50; regression: `region' overlay is lower priority than default 2013-11-14 22:57 Drew Adams 2013-11-15 7:41 ` Eli Zaretskii @ 2013-11-15 16:53 ` Barry OReilly 1 sibling, 0 replies; 39+ messages in thread From: Barry OReilly @ 2013-11-15 16:53 UTC (permalink / raw) To: 15899 [-- Attachment #1: Type: text/plain, Size: 494 bytes --] I agree having the region overlay at lowered priority is undesirable. I think most other overlays are longer lived, and during the shorter periods I use the region, it's the one I'm most interested in seeing. > Isn't it confusing that the region highlighting is non-contiguous > when an overlay is in its middle? Actually, it's worse when the other overlay is at either end of the active region, because then I can't tell for sure where the region began or ended unless I happen to remember. [-- Attachment #2: Type: text/html, Size: 581 bytes --] ^ permalink raw reply [flat|nested] 39+ messages in thread
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2013-11-15 21:21 ` bug#15899: 24.3.50; regression: `region' overlay is lower priority than default Drew Adams
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2013-11-15 17:14 ` Drew Adams
2013-11-15 19:33 ` Eli Zaretskii
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2013-11-15 15:55 ` Drew Adams
2013-11-15 16:43 ` Eli Zaretskii
2013-11-14 22:57 Drew Adams
2013-11-15 7:41 ` Eli Zaretskii
2013-11-15 13:54 ` Stefan Monnier
2013-11-15 14:40 ` Eli Zaretskii
2013-11-15 15:32 ` Dmitry Gutov
2013-11-15 16:40 ` Eli Zaretskii
2013-11-15 22:35 ` Dmitry Gutov
2013-11-16 8:49 ` Eli Zaretskii
2013-11-16 9:51 ` Jarek Czekalski
2013-11-16 10:42 ` Eli Zaretskii
2013-11-16 14:43 ` Jarek Czekalski
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2013-11-16 16:23 ` Drew Adams
2013-11-16 16:52 ` Eli Zaretskii
2013-11-16 22:01 ` Stefan Monnier
2013-11-16 22:42 ` Drew Adams
2013-11-16 10:25 ` Dmitry Gutov
2013-11-16 11:24 ` Eli Zaretskii
2013-11-16 13:49 ` Dmitry Gutov
2013-11-16 16:30 ` Drew Adams
2013-11-16 16:20 ` Drew Adams
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2013-11-16 16:24 ` Drew Adams
2013-11-16 1:25 ` Stefan Monnier
2013-11-16 9:06 ` Eli Zaretskii
2013-11-16 17:45 ` Stefan Monnier
2013-11-16 18:01 ` Drew Adams
2013-11-16 22:00 ` Stefan Monnier
2013-11-17 12:25 ` Daniel Colascione
2013-11-17 15:42 ` Stefan Monnier
2014-02-10 4:14 ` Lars Ingebrigtsen
2013-11-15 15:51 ` Drew Adams
2013-11-16 1:26 ` Stefan Monnier
2013-11-16 3:47 ` Drew Adams
2013-11-15 16:53 ` Barry OReilly
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