X stops receiving mouse clicks

[Marius Gedminas]

On Wed, May 13, 2009 at 06:25:05PM +0300, Marius Gedminas wrote:
> On Wed, May 13, 2009 at 10:11:42AM +1000, Peter Hutterer wrote:
> > On Tue, May 12, 2009 at 04:35:51PM +0300, Marius Gedminas wrote:
> > > Are there any debugging facilities for finding out which X client has
> > > the grab?
> > > 
> > > I once spent an hour killing all processes one by one until I found the
> > > one responsible (gnome-settings-daemon):
> > > http://mg.pov.lt/blog/xorg-snafu.html
> > 
> > if you have a second machine you can ssh+gdb in and look at
> > CLIENT_BITS(inputInfo.pointer->deviceGrab.grab->resource). this should give
> > you the client mask for the grab, and with xwininfo -root -children -all you
> > can then match that up with a running client (that's from memory, no
> > guarantees)
> 
> Thank you, this is more or less what I wanted to know in case the bug
> strikes again (probably unlikely).

The Bug took over a coworker's machine.  After killing a couple of
processes at random and failing to find the one that had the mouse grab,
I installed Ubuntu's debug packages and ran

  sudo gdb `which Xorg` `pidof X`
  (gdb) printf "%x", inputInfo.pointer->deviceGrab.grab->resource

(gdb doesn't know about CLIENT_BITS).

I got something like 0x2600000, and found a bunch of resources belonging
to xchat-gnome that had IDs of the form 0x260xxxx in xwininfo output.

Unfortunately, killing xchat-gnome did not release the grab --- instead,
reconnecting with gdb I got a different resource ID (one belonging to
Skype).  Killing Skype repeated the story: different resource ID
(Tomboy this time).  I gave up and told my coworker to restart X.

Marius Gedminas
-- 
Think different? I'd be happy if most people would just think...
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