menubutton .b -text "Blah" -menu .b.m
menu .b.m
.b.m add command -label "Tribble"
.b.m add command -label "Foo"
.b.m add command -label "Bar"
.b.m add cascade -label "Bittle" -menu .b.m.m
menu .b.m.m
.b.m.m add command -label "Stomp"

pack .b
bind .b.m <Motion> {+menuMove %W %y %s}
bind .b.m <Key-Return> {+set menu_help(current) -1}
bind .b.m <Key-space> {+set menu_help(current) -1}
bind .b.m <ButtonRelease> {+set menu_help(current) -1}
bind .b.m.m <Motion> {+menuMove %W %y %s}
bind .b.m.m <Key-Return> {+set menu_help(current) -1}
bind .b.m.m <Key-space> {+set menu_help(current) -1}
bind .b.m.m <ButtonRelease> {+set menu_help(current) -1}
set menu_help(current) -1

proc menuMove {w y s} {
    set oldy -1
    set idx 0
    set newy [$w yposition $idx]
    while {$oldy != $newy} {
	if {$y < $newy} {
	    set idx [expr $idx - 1]
	    handleEntry $w $idx
	    return
	}
	set oldy $newy
        incr idx
        set newy [$w yposition $idx]
    }
    set idx [expr $idx-1]
    handleEntry $w $idx
}

proc handleEntry {w i} {
   global menu_help
   
   if {$i > -1 && $menu_help(current) != $i} {
       set menu_help(current) $i
       set type [$w type $i]
       if {$type == "tearoff"} {
           puts "I'm a tearoff"
       } elseif {$type == "separator"} {
	   puts "I'm a separator"
       } elseif {$type == "command"} {
	   set name [$w entrycget $i -label]
	     if {$name != {}} {
		 puts "I'm over $name at $i."
	     } else {
		 puts "It's a separator at $i!"
	     }    
       }
   }
}