Forget list widgets. Use a Text widget. Pack all the buttons in it that you need. Even add buttons to move items up and down the list (in each row you would have a Checkbutton, an 'UP' Button and a 'DOWN' Button. When the user chooses to move an element a row up or down just create the Text widget from scratch again with the Buttons in the new order and redisplay it.
in reply to Re^2: Insert checkbutton into MListbox
in thread Insert checkbutton into MListbox