Well, I know what the bug is now: Clicking a fullscreen window from the win7 taskbar unsets our topmost status (wtf?) and it can't be restored programmatically. Great. :(
Updates to gesture confirmation logic (releasing a repeated scroll instantly confirms it; confirms show up in overlay)
Fix invalid gestures triggering confirmations.
Try a new way to keep the overlay on top.
Update the gesture overlay less often.
Hide the gesture overlay when it is blank.
Render the gesture overlay with a dark outline around all its contents so it's easier to see.
Change topmost behavior again.