A limited set of actions can assigned via macro commands. Incompatible actions are ommited from the generated macro. Also note that Macros are limited to 15 lines each.
I'm a left arm amputee - for 1-handed MMO mouse use (Logitech G600).
First attempt to make panels for MMO mouse with 2 3x4 hotbars and 1 6x2 for utility
1st: 1,2,3,4,5,Q,E,R,F,C,V,T 2nd: same but shift+
In this layout, I grouped the attack Motifs & Muses together, along with their action buttons, and your normal single target & group attacks and separated them from the other normal/non-motif/non-muse attacks. That neatly left room for Smudge on the main