On firefox there is an old bug where when you move a dragged file outside
the window the `dragleave` event is never emitted.
So we just use a timeout to reset the drag over state.
Also a small change: Use the ID of the main container instead of relying on tag name and class.
(The ID is guranteed as other APIs rely on it, while the class is just used internally).
Signed-off-by: Ferdinand Thiessen <opensource@fthiessen.de>
Ferdinand Thiessen
f7b7474cd3