bug#17609: 24.4.50; trunk r117096: disappearing cursor in X

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

>> There's still an issue. Pop-up notifications (notifications.el)
>> triggered by emacs make the cursor disappear. The cursor remains hidden
>> until emacs gets focus again.
> I'm not familiar with this code and don't know how the notifications popup
> window is created. Anyway, please try this tiny patch.

I'm still seeing disappearing cursors as well in trunk.
These seem to be remaining bugs in the new Xfixes code in Emacs.
I haven't tracked down a recipe yet, but I'll try and do that soon.
In the mean time I have another related problem:

Apparently the xfixes code itself is buggy in the xinerama X11 server:
- when I hit a key in Emacs, the mouse cursor is not "undrawn" and so
  the drawing of that cursor lingers on the screen until the next time
  this part of the screen gets redisplayed.
- better yet, the "undrawing" actually takes place but in the wrong
  screen (and with the wrong pixmap).  So in the right screen I get lots
  of ghost cursors and in the left screen I get matching "square blobs".
[ See https://bugs.freedesktop.org/show_bug.cgi?id=79703 ]

So, while I'm not necessarily advocating reverting to the non-xfixes
code, I think it would be good if the user could tell Emacs not to use
xfixes, in order to work around these bugs.


        Stefan