for a simple way to switch between GNU Screen 'screens' using Alt +
Arrow key, use the below key bindings in your .screenrc file

 
# Arrow keys to switch terminals (only works with X) 
# Alt + left 
bindkey ^[[1;3D prev 
# Alt + right 
bindkey ^[[1;3C next 

note:
- not use Ctrl + Alt + Left/Rigth Arrow as its used by GNOME to swap
virtual desktops
- nor firefox style as its used by GNOME Terminal for switching its tabs
- to find out what Alt/Fn/Ctrl characters equal what just execute cat
and start typing