How-to: Toggle the button face on a custom toolbar?

[Air_Cooled_Nut]

I have a custom toolbar that works fine. One of the buttons is a toggle: Click it and columns are hidden, click it again and the columns are unhidden -- very simple and it works. I would like to change the button face in response. So when the toolbar is first created it has a default button face. Clicking the button will run the macro and change the button face. Click the button again and the macro runs again and changes the button face back.

TIA!