It’s possible to remove right mouse action keybind, but not possible to bind it back to same action or any other, the only solution is to change it in config file manually or to reset keybind settings.
With the addition of Runic Invocation and it’s node Immutable Order, it would be nice get ability to bind any skill on bar to rmb, not just “Use ability 5”, since order of skills now matters.
Edit: Actually, i can’t even find where configs are stored now, found only graphics settings. Weird, i remember they all were stored locally.
Edit2: Found keybind settings in windows registry, managed to change rmb to 1st skill on my bar.
But also found another issue. With default RMB binding, you can hold RMB and press any other skill, RMB will be interrupted to cast it. Looks like this was implemented only to “Use ability 5” binding: after i changed RMB to 1st button, i can’t cast any skill while holding RMB.