bug#50660: 28.0.50; Text artifacting when the cursor moves over text under mouse face that originally displayed a box

[Eli Zaretskii]

> Date: Mon, 20 Sep 2021 10:07:27 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: larsi@gnus.org, 50660@debbugs.gnu.org
> 
> I guess you are saying that in the problematic scenario the
> pixel_width of the glyphs remains the same, even though the box
> dimensions have changed or the box attribute disappeared?  If so, I
> think the problem is not where the cursor is drawn or its position is
> computed, the problem is where we redraw a portion of text due to
> change of mouse highlight, i.e. inside draw_row_with_mouse_face and
> friends.

Actually, it looks like we already do everything we need to account
for the box border, when it exists, while drawing the glyphs (in
xterm.c/w32term.c).  The pixel_width of the glyphs is not used by the
back-end code which actually draws to the glass.  So the only place
which needs fixing is probably draw_phys_cursor_glyph and maybe also
erase_phys_cursor.  Assuming we are indeed talking about problems with
the glyph under the cursor.

Do you agree?