sashFormData.left = new FormAttachment(0, 200);
sashFormData.bottom = new FormAttachment(100, 0);
final Sash sash = new Sash(form.getBody(), SWT.VERTICAL);
sash.setBackground(toolkit.getColors().getBorderColor());
sash.setLayoutData(sashFormData);
sash.addListener(SWT.Selection, new Listener() {
@Override
public void handleEvent(Event e) {
((FormData) sash.getLayoutData()).left = new FormAttachment(0, e.x);
sash.getParent().layout();
}