cts the widget;
otherwise, sets the <B>-variable</B> to the <B>-onvalue</B>
Returns the result of the <B>-command</B>.
<P></DL>
<H3><A NAME="M13">WIDGET STATES</A></H3>
The widget does not respond to user input if the <B>disabled</B> state is set.
The widget sets the <B>selected</B> state whenever
the linked <B>-variable</B> is set to the widget's <B>-onvalue</B>,
and clears it otherwise.
The widget sets the <B>alternate</B> state whenever the
linked <B>-variable</B> is unset.
(The <B>alternate</B> state ma