AskMinMax adds 33 pixels in width and 47 pixels in height to all
superclass size fields and returns TRUE. Full Draw paints frame,
background and marker; update Draw erases the old marker and draws the
new one. Draw returns FALSE without full/update flags, otherwise TRUE;
drawing statuses are ignored.
SELECTDOWN inside the object enables mouse-move events. Any other button
code disables them. A delivered mouse move calculates an absolute angle
from the pointer around the knob center, clamps it to 0..270 and sets
Numeric_Value through ScaleToValue. It is not a relative drag
accumulator. The handler returns zero and does not delegate; Numeric
separately handles raw keys. There is no local pressed/drag flag check
on mouse moves, so callers must preserve the normal event-registration
lifecycle.