bug#23574: 24.5; Overzealous underlining in emacs-nox

[martin rudalics <rudalics@gmx.at>]

 > I do know about these, but I don't thunk we should document all those
 > details, since there are too many possible variations, and it's too
 > easy to be inaccurate.  "the last face used on the line" is good
 > enough, I think.

Including the quotation marks?

 > No, it need not do any of that.  The list is fixed for each redisplay
 > cycle of each buffer, so the list can be processed only once into a
 > bitmap of flags that tell which face attributes trigger face
 > extension.  Then all redisplay needs to do is compare the attributes
 > of the face loaded into the iterator object at end of each line with
 > these flags.

OK.  But with my property list approach a once calculated bitmap would
have simply overridden the face of the iterator object.  Yet cheaper but
less versatile.

 >> And then I thought about the - possibly silly idea - that a user might
 >> want to put a property like :background on all lines displayed,
 >> regardless of the last character's attributes.  Such a user would have
 >> to, before displaying the relevant buffer parts, go through all these
 >> lines and add that property to the newline (?) character of each line.
 >> Now I bet that the greater part of such users would put the property on
 >> all newline characters of the buffer instead of using something like
 >> ‘pre-redisplay-functions’ where even I couldn't tell whether it gets the
 >> window's start and end positions always right.
 >
 > Hmm.. not sure how this is related.

Suppose a user wants to use the same background for all spaces at the
ends of all lines of a buffer regardless of "the last face used on the
line".  How would she specify that?

martin