Tooltips don't disappear when mouse leaves window

[DallinYauney]

When moving my cursor to the left of the graphite window, and the mouse hovers over a tool in the toolbar, the name of the tool pops up and doesn't disappear until I move my mouse back into the window.

This means that if I want to have graphite on my right monitor, and use the left monitor, I have to navigate my mouse through the gap between the tools, or else have a tooltip there until I fix it.

This issue exists on desktop (Appimage & Flatpak) as well as web (Firefox & Chromium).

[Keavon]

I'll add a related minor bug: tooltips don't go away when the scroll wheel is rotated, but should.