Hey Ciro,
The code is still in the process of "cleanup", but if you want to clean up the graphics and come up with some new plans or suggestions on the rest of it/how it should work/appear/etc just post them up and I will do my best to roll it all into the application. I think the hardware "fullscreen" swap is a better approach to window mode, as you say; I'd also suggest that the whole "Window mode" should just be the same as the regular clock, but obviously made a little smaller so that it will fit in the window. That way you can leave the clock open in the background/etc and still have the time showing, switch between apps, etc etc.
On top of any graphic changes/tweaks/etc you want to make, please re-do the switches that I added (am/pm, loop/once, etc) as I did not have the proper font/colour to match your stuff... mine are close enough to be ok, but they're not exactly the same so good to clean it all up! I'm just in the middle of implementing the "mood" stuff, so that will be taken care of... is there anything else missing/needs to be changed in terms of functionality? (that way I can spend time working on the coding while you're doing the updated imagery/etc!)

(oh, at some point there are other things that could be added...i.e. ability to change time of snooze, etc... but that might be better to leave for the next "official" version... let's try and get a nice clean polished and working one out there, then focus on adding features/etc after that?)