or window.
<P></DL>
<H3><A NAME="M5">DESCRIPTION</A></H3>
<B>Tk_WindowId</B> and the other names listed above are
all macros that return fields from Tk's local data structure
for <I>tkwin</I>.  None of these macros requires any
interaction with the server;  it is safe to assume that
all are fast.
<P>
<B>Tk_WindowId</B> returns the X identifier for <I>tkwin</I>,
or <B>NULL</B> if no X window has been created for <I>tkwin</I>
yet.
<P>
<B>Tk_Parent</B> returns Tk's token for the logical parent of
<I>tkwin</I>.