Begin "Left click" in the 3D world.
- This function is called when left-clicking in the 3-D world. It is most useful for selecting a target for a pending spell cast.
- Calling this function clears the "mouseover" unit.
- When used alone, puts you into a "mouselook" mode until CameraOrSelectOrMoveStop is called.
Patch 2.0.1 (2006-12-05): Protected.
Patch 1.10.0 (2006-03-28): Requires a hardware event.