ch13 contains the following example programs:

xpopup:		a basic Motif popup menu without accelerators or mnemonics

xpopupcasc:	a Motif popup menu with a cascading submenu

xmenu1:		a simple spring-loaded popup menu using the Athena widgets

xmenu2:		a simple pulldown menu from an Athena command widget

xmenu3:		a simple pulldown menu using the Athena MenuButton widget

xmenu4:		a pulldown menu with a submenu, using the Athena widgets

xmenu5:		a spring-loaded popup menu with a submenu, using the
		Athena widgets

xmenu6:		an attempt at a pulldown menu identical to xmenu2 except 
		using XtCallbackExclusive with callbacks only and no 
		actions -- doesn't work because XtCallbackExclusive calls 
		XtPopup which can't pass the right parameters to _XtPopup
 		(even if you write your own callback it still won't work --
		this type of menu must use the XtMenuPopup action)  -- 
		fixed by XtPopupSpringLoaded

xmenu7:		a pulldown menu using the Athena SimpleMenu, MenuButton, 
		and all three Sme gadgets

xdialog:	a dialog box using the Athena widgets that is popped up
		with XtCallbackExclusive callback
