It's a standard widget in the guts of Tk. Perhaps the custom red dot is going to increase profits or save lives, but I really doubt it. Ask him if reinventing the wheel to implement whims is seriously worth your hourly pay rate.
Yes, it really is okay to tell someone, "after due and careful consideration" (show him a printout of this thread) "the best business-answer is: 'no.'" And let's face it, the first part of a request "can we do this?" is ... "CAN we do this?"