[mytreeoutside]

Good point Brian, and I appreciate the thought put into this. However, FWIW, controls are already (and inevitably) placed outside of 'steering wheel' reach; ie: action check boxes, the gear icon and a few other upper toolbar buttons.
I'm OK with it being on the right side if that's final, and I would keep my suggestion then that the arrow should point into the row that it's disclosing. But overall it's lovely :)