Advanced dummy mode's drift correct fixation is off in xpyriment and fullscreen

[eort]

When running the advanced dummy mode with the xpyriment back-end, the fixation dot that is used to simulate the drift correct doesn't correspond to the expected mouse position. So, when hovering with the mouse over the fixation dot, nothing happens. However, after I moved it somewhat to the left of the dot (maybe 100 px) the fixation was accepted. This happens only in fullscreen and regardless of where exactly the fixation dot is drawn.
Switching to PsychoPy back-end did solve it, though.

Here is a minimal example of the issue