bug#7464: 24.0.50; mouse highlighting vanishes upon unsplitting window

[Jan D.]

Hello.

Eli Zaretskii skrev 2012-03-29 20:47:
> > From: Stephen Berman<stephen.berman@gmx.net>
> > Cc: cyd@gnu.org,  7464@debbugs.gnu.org
> > Date: Thu, 29 Mar 2012 09:57:53 +0200
> >
> > openSUSE's 23.3 has GTK scroll bars, while I built 23.4 like I build 24,
> > i.e., without toolkit scroll bars.  So I rebuilt 23.4 with GTK scroll
> > bars, did the bug recipe and sure enough, now the mouse highlighting
> > remained, i.e., no bug.  Then I disabled the scroll bars in that build,
> > tested again, and got the bug again.  Then I rebuilt Emacs 24 with GTK
> > scroll bars, and now did not see the bug with them enabled but did see
> > it with them disabled.  So the answers to my questions above appear to
> > involve the presence vs. absence of GTK scroll bars.  (I guess Chong
> > Yidong also builds Emacs 24 with GTK scroll bars and tested the recipe
> > with them enabled, so that's why he did not observe the bug.)
>
> Unfortunately, I know almost nothing about how GTK in general and GTK
> scroll bars in particular are integrated into Emacs, and what, if
> anything, they change in how the Emacs display engine works.

It probably has something to do with the fact that Gtk+ scrollbars 
aren't handeled by the display engine and we therefore have to force a 
redraw of the scroll bars at certain points so the scrollbars look ok. 
Presumably one of these redraws does something that triggers a redraw of 
mouse highlight?  It might be that a redraw of the scroll bar generates 
some X expose/configuration event that in turn invokes the display 
engine.  I'm just speculating.


        Jan D.