[Reg: 4->5] XCB: compression of mouse move events is flawed

In Windows main QT loop will peeke WM_MOUSEMOVE event, the event is then pushed to windowSystemEventQueue and handled in separate (WM_USER+1) message. This means there might be multiple WM_MOUSEMOVE events pushed to windowSystemEventQueue before mouse move event is handled in (WM_USER+1).

Mouse move events should be dequeued from system message que (compressed) before mouse move event is handled in (WM_USER+1) message.

Another option is to compress all mouse move events in windowSystemEventQueue. I am attaching proposed patch (against qt 5.2.1).

Attached example reproduces the issue:
Run it with Qt5, click and move your mouse for few second and wait. You will see in the standard output: that the command will be executed several time. The same example on Qt4. You will see less output.

For similar mouse move:
Output In Qt4:
do something 0
do something 13

Output in Qt5:
do something 0
do something 1
do something 2
...
...
do something 12
do something 13