Refine tablet right click popup palette behavior.

Should be consistent now between AppImage and non-appimage
build environments (different QT versions?). Originally,
all tablet events were causing the time filter to get
stuck, which would ensure that users had 1 right click
event ignored. Also, event filter was inappropriately
installed twice despite only needing it installed
once due to refactor of popup palette design.

This should streamline the right click event eating
for the popup palette as a whole. If there's a regression
on windows (I'll have to check tomorrow!) then I'll have to
revert and try again.

BUG:441899