I’ve switched to use DWM, Dynamic Windows Manager, from GNOME on my laptop since the beginning of this month. So far I really enjoyed it.
Here are some commands I needed to know since I have an external screen connected ot this machine.
To change the focus to previous/next screen:
Mod1 + , Mod1 + .
To move applications from a screen to another, just add
Mod1 + Shift + , Mod1 + Shift + .