I see what you mean. Looking at TkDocs (not sure if this is an "official" or "officially endorsed" source or not), one of the Python examples in the "Tk Concepts" section (http://www.tkdocs.com/tutorial/concepts.html) says:

> Whether or not you save the widget object in a variable is entirely up to you, and depends of course whether you'll need to refer to it later. Because the object is inserted into the widget hierarchy, it won't be garbage collected even if you don't keep your own reference to it.

However, it very much looks like it may be related to what you said.