[platform-swt-dev] beginner SWT question about Canvas events

[Sean Smith <smithsd2@xxxxxxxxx>]

I'm a beginning graduate student working on a bioinformatics software
using SWT over swing.  I'm trying to learn to do simple things
have have run into, what I'm sure is a simple task.  On my shell I
have add a button, textfield, and a blank canvas.  What I need to
occur is input some value in the text field and allow it to define that
many number of arbitrary ellipses, and draw them to the blank canvas
upon the button click.  If the user enters another number I need
it to redraw the canvas, with now the new number of ellipses. 
Where I'm having trouble is the interaction from the button to the
canvas and drawing on the canvas based on the button event.  Any
suggestions would be much appreciated.