Set camera to follow an actor, then set that actor to follow your main character actor while
value is 1 and have the actor follow the mouse if value is 0.
If value 1 and key was pressed set value to 0 and if value 0 and key was pressed set value to 1.
Something along those lines.
I have yet to mess around with the mouse much in Stencyl but I think there's something
you have to do first to get it to work right; like an extra positional thing, but I've forgotten
what it was, so keep that in mind too.