What I'm trying to do is make a command for CRTL+SHIFT+TAB when I gesture to the top and left (that would be move to the previous tab in firefox) but its not going through, here is my lua script so far:
You have Control and Shift checked in your action definition, which means in addition to your drawing (gesture) you also have to press Control and Shift.
I'm guessing that's not your intent as it almost defeats the purpose of the gesture saving you time :)