I'm using Yakuake (it's a drop down terminal emulator) to manage my terminals and work in multiple terminals, switch between them... First you must launch the application and by clicking on F12 the window disappear and F12 again to appear.... etc.
Now after I've opened 2 sessions for my laptop and 2 session on my Raspberry, I can't for now switch to the window: after F12 nothing appears. If I reboot the laptop it will work fine but I have a lot of work that I don't want to lose.
I have found in the System Monitor that Yakuake is still running but I can't access it. I'm using Ubuntu 14.04.
update : i have installed also Guake and i have use F11 to make it appear/disappear but after a while the window cant' be displayed