F12 on the keyboard switches between the four different 3D modes.

Press F12 four times to cycle through all four modes and return to standard 2D.

The four 3D modes are:

  1. Standard 2D
  2. 3D Side by Side (SBS)
  3. 3D Top and Bottom (TAB)
  4. 3D to 2D cropping of SBS/TAB


See also forum thread