Hmmm, when the mouse pointer leaves the software-list widget (leaveEvent()), the "floating" snapshot-viewer is hidden... when you click an item (or move the cursor with the keys), it's shown again (provided there's a snapshot for the selected software), regardless if you "left the GUI" in between or not... perhaps I'm misunderstanding you, but that's how it's supposed to work and it does that here.

A mind is like a parachute. It doesn't work unless it's open. [Frank Zappa]