#### toggle mesh view, points view ####
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toggle variable (left-click):
  $edgesflag -- toggle surface mesh
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toggle variable (middle-click):
  $pointsflag -- toggle surface vertex points
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The upper middle MESH button (under REDRAW) has
two different functions.

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Left-click (toggle $edgesflag)
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A default left-click on the "MESH" button toggles
drawing of edges of surface polygons in addition
to the polygon, just above filled polygon.
Standard surface have so many polygons they won't
generally be individually visible without
zooming.

Control color of mesh with entries to right of
button ($meshr, $meshg, $meshb), which are also
used to color labels, and report and choose MGH
annotations,

Control the width of the mesh line in pixels
(default=1.1) with $meshline, which is accessible
(along with edgesflag) from a popup made on a
R-click (help) on the unlabeled tickbox at the
bottom of the middle right "phc" (phase contours)
box.

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Middle-click (toggle $pointsflag)
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An alternate middle-click on the "MESH" button
toggles the drawing of a point just above each
non-cut-away vertex.  This is mainly useful for
displaying sparse labels that don't have enough
vertices to be displayed as faces (at re-cut
time).  An example is when a uniq vtx label is
re-cut by a ctrl-left-click "C" on the "label:"
line.

Control color of vertex points with entries to
right of button ($meshr, $meshg, $meshb), which
are also used to color the mesh, labels, and
report and choose MGH annotations,

You can control points display and size (with
$pointsize) from a popup made on a R-click (help)
on the unlabeled tickbox at the bottom of the
middle right "phc" (phase contours).

Finally, a shift-middle click on the lower right
PTS button will turn on $pointsflag and increase
$pointsize to 2 for the purpose of finding stray
vertices when editing a label.
