Re: 21.1 mouse-movement locks up Emacs

[Jason Rumney]

eliz@is.elta.co.il (Eli Zaretskii) writes:

> On Sun, 9 Dec 2001, Jari Aalto+mail.emacs wrote:
> 
> 
> > (progn
> >   (defun test (event)
> >     (interactive "e")
> >     (message "mouse movement ok")
> >     (discard-input))
> >   (setq track-mouse t)
> >   (global-set-key [(mouse-movement)] 'test))
> > 
> > 
> > However, in 21.1 -q, running the code completely locks up Emacs.
> 
> This might be a Windows-specific problem (I don't have a Windows
> version around to try).

I can confirm that there is a Windows-specific problem with
mouse-tracking in 21.1. It is improved in CVS versions, but still not
perfect.

> What happens if you type C-g several times, when Emacs locks up?

The problem is not that Emacs has locked up, the problem is that it is
constantly receiving mouse-move events in the input queue (even when
the mouse is not moving), so there is little time for other input to
be processed. The bug is made worse by the setting of
`redisplay-dont-pause' on Windows to work around other related bugs.

> > by looking at the opening frame, the drag-bar constantly flickers
> > as if Emacs is in infinite loop.
> 
> This is a sign of a continuous redisplay, not of an infinite loop.

This is due to `redisplay-dont-pause' being set to t, combined with
the constant mouse-events triggering redisplay.

-- 
Jason Rumney