bug#11484: 23.4; Scrolling leaves traces of old text behind

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

>> That isn't a very good solution now that I think about it, as it would
>> require
> A redraw of the whole line just to draw the cursor.
> Are displays still slow enough that we have to care about graphics
> optimization at this level?

Sadly, in my experience, yes: with an E350 fusion processor running X11
and using server-side fonts, the drawing operations are sufficiently
slow that I can see that the frame is drawn top-to-bottom, so yes a full
redraw is very much visible.

IIUC the Xorg guys justify this by saying that these operations "never
happen" nowadays and that speeding them up would have to be at the
detriment of the more common operations.

If someone knows how to get misc-fixed-semicondensed-13 using xft
(i.e. client-side fonts), I'm all ears.


        Stefan


PS: BTW, I'm not sure if redrawing one more char on each side would
help, because depending on how the redraw is done, it might just push
the problem one char further.