Csurf "patch:" entry/dropdown (middle)

This entry contains the current patch (part of a
surface, typically flattened).  The dropdown
contains a list of all the patches in the current
$SUBJECTS_DIR, such as:

  full.patch.3d
  full.patch.flat
  occip.patch.3d
  occip.patch.flat

Selecting a patch from this dropdown auto-sets
the "Hemisphere Surf:" radio to either "viewcuts"
or "flattened" (and vice versa).

Since a patch is a subset of a complete surface,
and since it does not contain the full surface
specification (it has no face list), a full
surface must first be loaded (typically
"inflated").

All the patches in $SUBJECTS_DIR/<subj>/surf are
loaded into the dropdown on selecting a new
subject.  To update the dropdown if a patch has
been added after selecting the subject, reselect
the subject (<Return> in the "subject:" entry).

The "patch:" entries have had their hemisphere
prefixes stripped, so selecting RIGHT and
"occip.patch.flat" loads this surface and patch:

  $SUBJECTS_DIR/<subj>/surf/rh.inflated
  $SUBJECTS_DIR/<subj>/surf/rh.occip.patch.flat

===================================
Startup Details
===================================

Here is the command line that is typically used
to start tksurfer with a patch:

cd $SUBJECTS_DIR/<subj>/scripts
env \
  doublebufferflag=1 \
  dividequadsflag=1 \
  undividequadsflag=0 \
  newquadoutputflag=0 \
  writefloatpatchflag=1 \
  smallscreenflag=0 \
  tiffoutflag=1 \
  black2transparentflag=0 \
  tksurferinterface=mini \
  patchname=occip.patch.flat \
  /full/patch/to/tksurfer martys09 rh inflated \
  -tcl /tmp/TmpTclSurf.64484

The tmp tcl script referenced above looks like
this:

 source $CSURF_DIR/lib/tcl/setdefpatchview.tcl
 setfile patch ~/surf/rh.occip.patch.flat
 read_binary_curv
 read_binary_patch
 open_window
 restore_zero_position
 rotate_brain_x -90
 rotate_brain_z $flatzrot
 translate_brain_x $flatxtrans
 translate_brain_y $flatytrans
 scale_brain $flatscale
 set cslope 3.0
 set offset 0.30
 set cvfact 1.30
 set light2 0.8
 redraw
