final Sash sash = new Sash(composite, SWT.VERTICAL);
sash.setLayoutData(new GridData(GridData.FILL_VERTICAL));
sash.setBackground(composite.getDisplay().getSystemColor(SWT.COLOR_LIST_BACKGROUND));
// the following listener resizes the tree control based on sash deltas.
// If necessary, it will also grow/shrink the dialog.
sash.addListener(SWT.Selection, new Listener() {
/*
* (non-Javadoc)
*
* @see org.eclipse.swt.widgets.Listener#handleEvent(org.eclipse.swt.widgets.Event)
*/