bug#11822: 24.1; emacsclient terminal mode captures escape characters as text

[Stefan Monnier <monnier@iro.umontreal.ca>]

>> >   /* Contrary to expectations, a value of "false" can be detrimental to
>> >      responsiveness since aborting a redisplay throws away some of the
>> >      work already performed.
>> But that's because the effect was different from what is being
>> discussed here (at least in theory): interrupting redisplay between
>> windows wouldn't throw away work, AFAIK.
> What Ken suggests is not an interruption between windows, it's
> interruption in the middle of recomputing faces.  That's much worse.

I think he suggests several things.

One of them is to redisplay frame-by-frame, starting with the selected
frame and checking for pending input between each frame.

Another is to do decompose the redisplay of a given window into
chunks (e.g. cut at those points where we're waiting for a reply from
the X server) that can be interrupted.  IIUC by "interrupted" he doesn't
mean to abort what we're doing, but only to suspend it.

What we need to remember from redisplay-dont-pause is that we need to
avoid doing work and throwing it away before the result is shown on
the display.  In the case of redisplay-dont-pause, the reason it's
thrown away is that by the time we got back, the work we'd done
(refreshing the matrices) often/usually needed to be redone.

If we only interrupt after refreshing the display of a window and before
starting to recompute the glyph matrices of the next, then I think we
avoid this risk.


        Stefan