Is there any workaround for this problem?

As is says in the documentation: "-background => COLOR -- Defines the background color for the control. Note that not all controls support background and foreground colors."

For standard controls like Push Buttons, Radio Buttons etc. the buttons are drawn for you by system classes, using the colors and styles defined by the system pallete. This is all a part of the 'look&feel' of the interface that is applied right across the desktop and all applications. It allows users to configure the desktop to suit their preferences and requirements. Eg. a color blind person might ensure that the foregraound/background combinations are such that they don't exacerbate their particular handicap.

You could go the route of creating your own widget that acts like a button, but then you've the responsibility for doing all the drawing, and event processing which is a complex thing to tackle.

So the question to ask yourself is, are your users going to be impressed by you overriding their choice of control colors?