xserver 1.6 branch and mouse position zapping

Colin Guthrie gmane at colin.guthr.ie
Mon Dec 29 01:31:20 PST 2008

'Twas brillig, and Colin Guthrie at 26/12/08 15:25 did gyre and gimble:
> 'Twas brillig, and Peter Hutterer at 26/12/08 00:25 did gyre and gimble:
>> On Wed, Dec 24, 2008 at 11:41:10AM +0000, Colin Guthrie wrote:
>>>> Just built the 1.6 branch + recent mesa snapshot and other such stuff.
>>>> It seems to be stable enough just now, but one thing that's been 
>>>> affected is how the mouse positions itself to top-left after a certain 
>>>> operations.
>>>> So far I've found odd behaviour when doing:
>>>>   * Compiz cube dragging (ctrl+alt+click and drag)
>>>>   * Compiz window moving (alt+click and drag)
>>>>   * Compiz window moving (click and drag on title bar)
>>>> When this happens the mouse just jumps to the top left, but not always 
>>>> immediately.
>>>> While this could easily be a compiz issue (I certainly cannot reproduce 
>>>> in metacity), I'm guessing it's related to the xserver change. I have 
>>>> also updated to the latest input-proto and other such stuff too.
>>>> Is there an obvious starting point to look further into this? Or perhaps 
>>>> it's a known issue?
>> can you reproduce this with any other client too? It's most likely an X server
>> issue, but a good reproduceable behaviour in a client other than compiz makes
>> it easier for me to find the bug.
>> My first guess is that event replay after synchronous grabs have the wrong
>> coordinates.
>> You say it doesn't always happen immediately: try to move particularly fast or
>> slow to see if that can trigger it.
> It's really hard to describe! Speed of movement doesn't seem to make 
> much odds but I have narrowed down the behaviour to the "Snapping 
> Windows" compiz plugin. Disabling this makes things a lot more stable 
> but there are still some issues.
> Every time I move the cube face, either with a window drag to the edge, 
> or with a keystroke, the mouse pointer zaps to the top left.
> I can't duplicate the behaviour in metacity, but I've not tried in Kwin4 
> yet.
> I'm not 100% certain it's a xserver issue here and perhaps compiz is 
> hooking into something it shouldn't be, but it's certainly a regression 
> of sorts.
> Not really sure how to give you better info to help diagnose :(
> I'll try asking on compiz IRC to see if anyone else is experiencing the 
> same issues.

OK, some strange things happened.

I applied the patch for the locale/layout settings 

and now things work fine :s

There have been other changes on my system but nothing that would jump 
out at me as being overly relevant.

If I have time, I'll go back to a server without this patch and see if 
the problem returns.

I have also updated libcompizconfig which was updated on the 26th 
December to a buggy build, but as I originally noticed this behaviour on 
the 24th December, I doubt this is actually relevant!



Colin Guthrie

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