NAME
       WM_CLOSE -- close a window

   SYNOPSIS
       DoMethod( winobj, WM_CLOSE );

   FUNCTION
       close the window of this object. the gadgets are not disposed,
       only detached of a window. If the window is sharing a message
       port with another window, the port will be cleaned of message
       intended for this window. If the window was iconified, the icon
       will be removed.