thank you for your replying maybe I have not enough experience to understand your advice easily now I got it what the transparent option is. I tried several change but nothing changed could you be more specify? I was thought I need to set a style option on circle but draw-bitmap doesn't have such a transparent option. and I tried following modification but does nothing (new select% (parent f) (min-width (image-width chipset)) (min-height (image-height chipset)) ) to (new select% (parent f) (min-width (image-width chipset)) (min-height (image-height chipset)) (style '(transparent))) thanks in advanced , Mathew Kurian <bluejamesbond@gmail.com>님이 작성: > Greetings, > > According to Racket Docs: > > > ----Just set style----- > > > 'transparent – the canvas is automatically “erased” before an update using it’s parent window’s background; the result is undefined if this flag is combined with 'no-autoclear > > > > Hopefully that helps. > > Sincerely, > > > Mathew Kurian > -- > Mathew Kurian > Seven Lakes High School > > Cell: 8324932862 | Home: 2814929526 > Do all the good you can, by all the means you can,  > In all the ways you can, in all the places you can, > > At all the times you can, to all the people you can, > As long as ever you can." :) John Wesley > > Please be sure to visit SLHS Red Cross Association > > >   >   > > > > >