[Gimp-developer] Bug affecting systems with two monitors, and a potential fix

[David Polberger]

Thanks for your reply, Martin.

Martin Nordholts wrote:
> Without having looked closely at the issue and just reading your
> analysis of it, the bug appears to be in the libs GIMP use. Might be the
> GTK X backend, or even as deep as X itself, perhaps in the form of a
> mouse driver bug or something.

I built and debugged both GTK (GDK) and XLib, and neither are to blame. 
GDK's X11 backend simply calls XLib's XGetMotionEvents(), which merely 
sends a message to the X server. I've verified that the information 
returned from the X server is to blame, not any of the libraries.

This means that the bug is in the X server itself. 
devices.c:ProcGetMotionEvents() in the X server seems to get its 
information from a virtual function, *mouse->valuator->GetMotionProc, so 
this may have something to do with the mouse device code. If I find 
time, I will try to debug the X server.

(I have tried to file a bug report with their Bugzilla server, but for 
whatever reason I can't create an account. I'll try again later.)
--
David Polberger