Toolbar should only fade in if mouse at top border

[humdinger]

This is hrev42282.

ShowImage's toolbar should mimick Web+'s behaviour in full screen mode:

• only fade in if the mouse pointer is moved to the top of the screen
• fade out immediately when the mouse is moved off the toobar

At the moment the toolbar pops up whenever you use the mouse, when you may just want to point to something, pan a zoomed image or accidentally move the mouse too much when zooming via mouse wheel.

[leavengood]

Implemented in hrev42307.

[stippi]

This behavior was on purpose. I wanted to give users a clear way out of full-screen. I estimated, that it was more likely that users just watch slide shows full-screen, and any thing else would be pretty unlikely, like zooming, panning, selecting, and in the rare case one wouldn't mind the tool bar. Websites on the other hand require a lot of mouse interaction, so I view the situations as quite different. I wouldn't mind if we keep the new behavior, I just wanted to make sure the rational of the old behavior is documented.

[axeld]

Just for the record: while I think your reasoning is sound, as a user, I would prefer how it's done now.