python tkinter: Custom menu while pulling down -

i'm learning creating software python , tkinter. need change menu items different conditions, not find easy way it. well, let me try explain question using example:

like shown in figure, have listbox on left , listbox on right. have menu move items around, commands "move right", "move left" , "exchange". following conditions considered:

1. when items selected in left listbox, want command "move right" enabled, shown in figure.
2. when items selected in right listbox, want command "move left" enabled.
3. when items selected in both listboxes, want commands enabled.
4. when no item selected, want commands disabled.

i know can work done binding events "listboxselect" , "button-1" functions, , use functions configure menu. complex work when have 5 listboxes in actual software. wondering whether there easy way this, overloading functions in tkinter.menu class (i tried overloading post(), grid(), pack() , place(), none of them works).

any idea welcomed.

i think want use postcommand modify menu appropriate. if you're going have multiple listboxes, simplest solution may implement own class. here's rough idea:

class editmenu(tkinter.menu):      def __init__(self, parent, listboxes, **kw):         self.commandhook = kw.get('postcommand', none)         kw['postcommand'] = self.postcommand         super(editmenu, self).__init__(parent, **kw)         self.listboxes = listboxes         self.add_command(label="move right", command=self.move_to_right)         self.add_command(label="move left", command=self.move_to_left)         self.add_command(label="exchange", command=self.exchange)      def postcommand(self):         in xrange(3):             # checks each entry             # , set state either tkinter.disabled or tkinter.normal             self.entryconfig(i, state=state)         if self.commandhook not none:             self.commandhook()      # implement 3 functions here 

if start add more items, you'll want create class each menu item. in class put in logic enable/disable , callback function implementation. comment if you'd see example.