The attached "MouseTest.tap" successfully acts as a simple "Etch A Sketch" program on GTK+ 2.x, but on GTK+ 3.x / X11 the y-values are random, changing even when the mouse isn't moved.
(I have the changes from bug #435 applied; see also bug #438 for the GTK+ 3.x / Wayland behaviour)
Diff:
Diff:
A regression caused by half doing the changes in bug #435; fixed by completing that change properly.