layout();
layout(false);
public void setTopCenter(Control topCenter) {	checkWidget();	if (topCenter != null && topCenter.getParent() != this) {		SWT.error(SWT.ERROR_INVALID_ARGUMENT);	}	if (this.topCenter != null && !this.topCenter.isDisposed()) {		Point size = this.topCenter.getSize();		this.topCenter.setLocation(OFFSCREEN - size.x, OFFSCREEN - size.y);	}	this.topCenter = topCenter;	layout();}