Hi, I just added an entry to the comments in the Scheme cookbook in  the 'GUI: <a name="Aggregating_Widgets_in_a_Single_">Aggregating Widgets in a Single Widget' section </a> -- <a href="http://schemecookbook.org/Cookbook/GUIWidgetAggregation"> http://schemecookbook.org/Cookbook/GUIWidgetAggregation</a> It is an example of a simple widget created from drawing toolkit elements, rather than existing widgets.I'd appreciate any comments/edits to improve it. (technically or pedagogically) Cheers, Stephen <div class="scheme"><pre>; make new widget'scatter-chart%' ;; do this all in Pretty Big language (DrScheme only) (define scatter-chart% (class pane% () (init-field parent ) ; Make the drawing area (super-instantiate () (parent parent) ; instantiate this FIRST [min-width 100] [stretchable-width #f] (min-height 200) [stretchable-height #f ]) ;; internal data (define list-of-points '()) ;; start with empty list (define canvas (new canvas% [parent this] (paint-callback (lambda (canvas dc) (draw-chart))) [min-width 100] [stretchable-width #f] [min-height 200] [ stretchable-height #f] )) (define dc (send canvas get-dc)) ; Get the canvas's drawing context ; Make some pens and brushes for use later (define no-pen (make-object pen% "BLACK" 1 'transparent)) (define blue-brush (make-object brush% "BLUE" ' solid)) (define yellow-brush (make-object brush% "YELLOW" 'solid)) ;; public methods ;; add-point : new-point (define/public (add-point new-point) ( set! list-of-points (cons new-point list-of-points)) ;; add to the list (send dc draw-rectangle 0 new-point 200 1)) ;; and draw the line ;; draw-chart : draw a chart based on the list of integers supplied ;; see <a href="http://download.plt-scheme.org/doc/371/html/mred/mred-Z-H-397.html">http://download.plt-scheme.org/doc/371/html/mred/mred-Z-H-397.html</a> (define/public (draw-chart) (send dc set-pen no-pen) (send dc set-brush blue-brush ) (send dc draw-rectangle 0 0 100 200) ; big blue rectangle (send dc set-brush yellow-brush) (map (lambda (y) ( send dc draw-rectangle 0 y 200 1)) ; draw a line for each integer. list-of-points )) (draw-chart))) ; draw it for the first time when this class is instantiated ; Make a frame (define frame (new frame% [label "scatter-chart% Example"] [width 100] [ height 200])) ; Show the frame (send frame show #t) ; Wait a second to let the window get ready ;(sleep/yield 1) (define new-my-widget (new scatter-chart% (parent frame) )) ; instantiate the widget in the frame (define new-his-widget (new scatter-chart% (parent frame) )) ; make another one (send new-my-widget draw-chart) ; Draw the face (define (go) (map (lambda (y) ( send new-my-widget add-point y) ; add a point at a time (sleep/yield 0.05)) ; draw it slowly '(10 30 22 77 78 79 17 65 97 54 55 56 57 91 33 55 95 99 125 155 157 159 188 187 186 191))) ;; list of datapoints (go) ;; !!! </pre> </div> -- Cheers, Stephen -- Stephen De Gabrielle <a href="mailto:s.degabrielle@ucl.ac.uk">s.degabrielle@ucl.ac.uk</a> Telephone +44 (0)20 7679 5242 (x45242) Mobile                  079 851 890 45 <a href="http://www.uclic.ucl.ac.uk/annb/MaSI.html">http://www.uclic.ucl.ac.uk/annb/MaSI.html</a> University College London Interaction Centre Remax House - 31/32 Alfred Place London - WC1E 7DP