Short description of error
There is new option in hotkey for 3D manipulator:
But it is not possible set it to same bahviour as previous version, when you have your custom hotkeys.
For rotate / pan / zoom in viewport I use L/M/R mouse button + some key on the keyboard. Similar controls is in the Houdini (space + mouse button)
But with new 3D Manipulator hotkey options, even I am holding key + mouse button, I still move with manipulator. Blender is filtering only Shift / Ctrl / Alt / Cmd, but not another keys. So Right Mouse button with Space is same as Right Mouse Button only.
As I mentioned before, it works great in 2.78.