I'm developing a special-purpose button widget derived from a Tk Label widget. I would like for the attribute -background to refer to the background color of the button in the 'off' state. So I use ConfigSpecs with 'PASSIVE' to put the value of this attribute in the new widget's hash when the user invokes configure. Unfortunately, doing so blocks access to the -background attribute of the underlying Label widget in my module-level code when I invoke configure there. (I need to do this to change the color of the underlying Label.) Is there a way to bypass Tk::Derived's configure so I can get to the underlying attribute without having to rename my attribute '-offbackground' (or somesuch) or resorting to a composite, frame-based widget?