Csurf current hemisphere (upper middle)

This chooses the which hemisphere to display
(LEFT, RIGHT) upon clicking SURFACE.  It also
picks which surface to load initially when VOLUME
is used to display a 3D MRI volume.

If BOTH is clicked, the hemispheres will be
displayed in sequence starting with the RIGHT.
To see the LEFT, kill tksurfer (purple button or
upper left 'x' on tksurfer interface).

Finally, the "hemi:" select picks which
hemisphere to present saved bitmaps (tiffs) for,
when using:

  SubjectTools -> View Saved Subj Bitmaps
  SessionTools -> View Saved Funct Bitmaps
  CrossSessTools -> View Saved Avg Bitmaps

To present all saved bitmap files, even those not
containing a hemisphere specification, select
"hemi:" BOTH.
