>     gouessej wrote
>     Yes it clarifies the problem but I would like to know what happens if you
>     replace SWT GLCanvas by org.eclipse.swt.widgets.Canvas to be absolutely
>     sure that the bug comes from the SWT GLCanvas and not from
>     org.eclipse.swt.widgets.Canvas. com.jogamp.opengl.swt.GLCanvas extends
>     org.eclipse.swt.widgets.Canvas, that's why I wonder whether the bug
>     doesn't come from SWT.
>
> ok
>
> I tested to replace the glcanvas code from above with
>
> Canvas canvas = new Canvas(scrolledComposite, SWT.None);
> canvas.addPaintListener(new PaintListener() {
> @Override
> public void paintControl(PaintEvent arg0) {
> GC gc = arg0.gc;
> gc.setBackground(arg0.display.getSystemColor(SWT.COLOR_RED));
> gc.fillRectangle(100, 100, 50, 50);
> }
> });
>
>
> and it worked as expected.
>
> So it has to do something with the way how JOGL determines the window position
> and size. As internally the ScrolledComposite calls the "setLocation" method
> of the Widget to move it around within the ScrolledComposite.