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tickbox variable: $labelalpha -- label transparency
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default: 128

The "tran" entry (upper left) determines
transparency (alpha) of labels when they are
displayed as a single-color transparent overlay
using the label line "D" button, where 255 is
opaque and 0 is completely transparent
(invisible).

This transparency value is used when a label is
read in.  By changing the value before reading a
second label, that second label can be displayed
with a different transparency.

This is analogous to how the "r", "g", and "b"
fields to the right of MESH are used to get
different color labels during label reading with
the "D" button.

To reset the transparency of all labels (e.g., an
annotation) currently displayed to a single
value, enter that value and do a <Return> in the
"tran" entry (tcl function: set_annot_alpha
<alpha>).

Transparency/alpha values in annotation files
(typically 0) are ignored.
