Tk should support setting the _MOTIF_WM_HINTS property
as part of [wm attributes] on Unix/X; IIRC many window
managers (aside from mwm and dtwm/CDE) support this
nowadays as a way of getting client-specified styles
going, and the structure is easy enough to figure out
given a set of Motif header files.

(submitted so the idea doesn't get lost.)

Obsoleted by <tt>wm attributes $win -type</tt>, which uses a <a style spec system</a>.