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entry entry variable: $surflinewidth -- pix
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default: same as magnification

The "linewidth:" entry (only visible on fn-F4
interface) sets the thickness of the line used to
display surface(s) in pixels.

By default, this will be set to the current
magnification (default magnification of 2 sets
$surflinewidth to 2).

A thicker line can be useful when SURFPAINT
(fn-F4 only) is used to display curvature or
fieldsign data on the line.
