Question on Pmw Balloon Binding

[Gillou]

The reason...

> button = Button(frame, text="Button").pack()

pack() method of widgets return None, NOT the packed object. You can't use
any more your Button widget :((
use directly this kind of construct for widgets you don't need anymore after
packing (labels...)

> button = Button(frame, text="Button")
> button.pack()

Here "button" is a widget. You can play with it later in your code.