Feature Request: Support modifiers keys on Mouse Button Remap

[amoeba]

I'd like to be able to map the combination of pressing a mouse button while holding a modifier key (cmd, ctrl, alt, shift) to a key combination. e.g., option+button4 mapped to cmd+[. This is a BetterTouchTool feature and I discovered this gap while evaluating Multitouch.

I expected to be able to find a way to do this in the highlighted area below using either a radio or checkbox control:

[rxhanson]

Good point, I'll add this to my backlog.