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
fTable.addSelectionChangedListener(fListViewerAdapter);
			
			fTable.setInput(fParentElement);
			
			if (fViewerSorter != null) {
				fTable.setSorter(fViewerSorter);
			}
			
			fTableControl.setEnabled(isEnabled());
			if (fSelectionWhenEnabled != null) {
				postSetSelection(fSelectionWhenEnabled);
			}
		}
		return fTableControl;
	}
	/**
	 * Returns the internally used table viewer.
	 */ 		
	public TableViewer getTableViewer() {
		return fTable;
	}
	
	/* 
	 * Subclasses may override to specify a different style.
	 */
	protected int getListStyle(){
		int style=  SWT.BORDER | SWT.MULTI | SWT.H_SCROLL | SWT.V_SCROLL ;
		if (fTableColumns != null) {
			style |= SWT.FULL_SELECTION;
		}