xserver 1.6 branch and mouse position zapping

Colin Guthrie gmane at colin.guthr.ie
Mon Dec 29 01:42:28 PST 2008

'Twas brillig, and Colin Guthrie at 29/12/08 09:31 did gyre and gimble:
> '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 
> http://bugs.freedesktop.org/show_bug.cgi?id=19048
> 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!

Tell a lie. It seems I built the xserver against an older 
x11-proto-devel that did not have the latest dri2proto.. Not sure it 
will matter but will rebuild and see what happens :)



Colin Guthrie

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