Bug 27491 Cannot add classpath variable to project
build id : 200212020010 The buttons OK and extend... are always disabled in the add variable dialog
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/dialogfields/ListDialogField.java
separator.setLayoutData(gd);
		return separator;
	}			
	/**
	 * Returns the composite containing the buttons. When called the first time, the control
	 * will be created.
	 * @param The parent composite when called the first time, or <code>null</code>
	 * after.
	 */	
	public Composite getButtonBox(Composite parent) {
		if (fButtonsControl == null) {
			assertCompositeNotNull(parent);
			
			SelectionListener listener= new SelectionListener() {
				public void widgetDefaultSelected(SelectionEvent e) {
					doButtonSelected(e);
				}
				public void widgetSelected(SelectionEvent e) {
					doButtonSelected(e);
				}
			};
			
			Composite contents= new Composite(parent, SWT.NULL);
			GridLayout layout= new GridLayout();
			layout.marginWidth= 0;
			layout.marginHeight= 0;
			contents.setLayout(layout);
			
			if (fButtonLabels != null) {
				fButtonControls= new Button[fButtonLabels.length];