tivates whenever the mouse passes over it and deactivates
whenever the mouse leaves it.
<P><LI value="2">
Pressing mouse button 1 over a menubutton posts the menubutton:
its relief changes to raised and its associated menu is posted
under the menubutton.  If the mouse is dragged down into the menu
with the button still down, and if the mouse button is then
released over an entry in the menu, the menubutton is unposted
and the menu entry is invoked.
<P><LI value="3">
If button 1 is pressed over a menubutton 