Fix fullscreen window position (#873)

[spasche]

From my testing on a Fedora 25 (Gnome 3.22) system, it looks like placing the window in fullscreen from the idle callback is too soon and always places the window on monitor 0 (left one).
If gtk_window_fullscreen() is called from the "map-event" event, it places the window on the same monitor where the window was.
I didn't experience the black border issue mentioned in the previous comment. Using a signal instead of the idle callback means we don't need to track the event source identifier, which removes some code.

I'd be happy if somebody could test this on other environments (non Gnome, or pre-3.22 versions).

[antenore]

Thanks a lot Sylvain!

I'll test it in the next days on some different WMs.

[antenore]

#124 #241 #873

[antenore]

Tested on Xfce 4.12 (xfwm4), Gnome 3.18.2 and i3wm on FreeBSD.
In some hours I'll do some other tests, but for me can be merged.

@giox069 what do you think? How is on Unity and Gnome Shell?

[antenore]

@giox069 I'm merging this, it behave correctly in all the scenarios I've tested.
@spasche Remember me to add your name in the AUTHORS and remmina_about.glade files before the next release.

[spasche]

Great! Thanks for testing and merging.

[giox069]

👍