Add automatically hide on-hover option
Basically an inverted hide.
The reason is for always-on information panels that don't need to be clicked and might block things behind them. For instance: I have a panel just for the time, while it usually doesn't block anything from being clicked, sometimes things are visually hidden so it'd be nice if it'd slide off-screen if I hovered my mouse over it (settings can still be modified by opening panel settings from elsewhere, would be even more useful if panels could have names).
The Opacity enter option is not useful here as mouse input is still absorbed even if enter opacity is set to 0 (also still requires compositing).