Switching between pan and orbit while holding MMB In previous versions of Blender I've used, pressing or releasing Shift while holding  MMB would switch between orbiting and panning, without needing to let go of  MMB. In my fresh installation of Blender 2.77 (on Ubuntu Linux 16.04), pressing or releasing Shift while holding  MMB does nothing; if I wasn't holding Shift when I pressed down  MMB, then it would stay in orbit mode, no matter what. How would I restore the old behavior?
Got to File > User Preferences > Input > 3D View > View 3D Rotate Modal and add a new key combination

Set it to Switch to Move and add any key combination you like.

I did not succeed settings it to work with the Shift key though, it seems to not like "modifier keys" on their own, but most other combinations will probably work.