Re: Simplification to mouse-avoidance-mode (patch) + redisplay bug?

[storm@cua.dk (Kim F. Storm)]

Richard Stallman <rms@gnu.org> writes:

> If you think your patch is correct, would you please install it?
>
>     I notice that the final cursor shape often gets it wrong if I set the
>     style to "cat-and-mouse", it seems to happen if the cursor passes over
>     an area (eg. void or a mode line) along the chosen path.  That looks
>     like a redisplay bug.
>
> You're the expert on redisplay--could you debug it (and ack)?

I've debugged this far -- and need an X-pert (Jan?) to take over:


mouse-avoidance-mode 'animate uses set-mouse-position to move
the mouse cursor in ~10 steps to reach its end position.

If I type very slowly, approaching the window cursor to the mouse
cursor -- and don't type anything while the mouse cursor is moving,
everything works, i.e. the mouse cursor shape at the final destination
is ok.

If I type more quickly, the mouse cursor still moves in steps, but
it may end up with any of the cursor shapes it had along the path.

I put some trace output into xterm.c, and it seems that (in the first
case) for each call to x_set_mouse_position (which calls
XWarpPointer), the event loop receives a MotionNotify event
(event.type = 6) with the new mouse cursor position.

.. unless I hit a key while the mouse is moving (the second case).

As soon as emacs gets the key event (event.type = 2), no further
MotionNotify events are delivered for the remaining mouse positions
along the path.

This looks like an X bug.  This is the Xfree server from redhat 9.0.

A work-around could be to unconditionally call "note_mouse_movement"
in x_set_mouse_position ?



In GNU Emacs 22.0.50.8 (i686-pc-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2006-05-09 on kfs-l.imdomain.dk
X server distributor `The XFree86 Project, Inc', version 11.0.40300000
configured using `configure  'CFLAGS=-O0 -g''

-- 
Kim F. Storm <storm@cua.dk> http://www.cua.dk