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switch variable: $colscale -- funct color scale
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switch value: 14 => color lookup table (complex phase)

The "ltw" (color lookup table, complex phase) is
designed for user-entered complex-valued custom
complex *phase* -> rgb color look up table.

Left-click the "Col:" label to get a popup to set
this scale, and R-click on the "ltw" radio button
there for details on how to use this color scale.

Rarely used

On the fn-F3 large interface, a middle-click
(instead of a left click) on the "ltw" button
instead selects $colscale=13, which is for a
custom complex *amplitude* -> rgb color look up
table.
