Without mouse mouvement, notifications doesn't close and prevend gnome to sleep
I never understand the reason behind gnome 3.XX notification behavior.
Don't want to close/hide itself if there's no mouse movement. Close/hide when you use your mouse or if your cursor goes hover the notification to unroll it.
Why you can't use the same notification behavior of every other desktop environment : time + auto hide without any hovering cursor instant hide.
Moreover, if a notification appears when you go away from mouse, gnome doesn't want to go to sleep because the notification don't want to close/hide itself.
Edited by Mathieu Provençal