QMouseEvents can occur before QTabletEvents on Linux

Steps to reproduce / test case:

According to the documentation for QTabletEvent:

Qt will first send a tabletEvent then, if it is not accepted, it will send a mouse event.

However, mouse events can occur before the corresponding tablet event.

With the attached program, running "./tabletEvents ignoreTabletEvents", and touching down the stylus can produce the following output. Note that the mouse press event occurs before the tablet press event.

(preceding events omitted)
xevent serial=237 type=6 MotionNotify x=143,y=352
xevent serial=237 type=105
time=1592 tablet move event x=143,y=352 pressure=0 ignored
xevent serial=238 type=6 MotionNotify x=145,y=354
xevent serial=238 type=105
time=1601 tablet move event x=145,y=354 pressure=0.389432 ignored
xevent serial=238 type=4
time=1601 mouse press event x=145,y=354 accepted
xevent serial=238 type=103
time=1601 tablet press event x=145,y=354 pressure=0.389432 ignored
(following events omitted)

Also, if the first occurrence of a tablet move event with non-zero pressure is accepted, the immediately following mouse press event will not occur.