&& expander.getContent() != null) {
final boolean expanded = expander.isExpanded();
shadeButton.setButtonData(expanded ? collapseImage : expandImage);
expandTransition = new ExpandTransition(expanded);
expandTransition.start(new TransitionListener() {
@Override
public void transitionCompleted(Transition transition) {
expander.setExpanded(!expanded);
expandTransition = null;
}