LXRandR is a very basic monitor config tool utilizing X RandR extension.
It's a GUI frontend of the command line program xrandr. LXRandR can let
you change the screen resolution on the fly. Besides, when you run
lxrandr with external monitor connected, its GUI will change, and show
you some quick options to get your projector working correctly.
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Note that this will not work on each and every installations but it does
its job for me.
ok jasper@