Bug 166015 Refactor designer actions to eclipse command framework
Eclipse command framework provide a more explicit way to manage UI actions contributions, we can take it's advantage to make our actions code more clean and maintainable.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/internal/ui/views/actions/DeleteAction.java
* Create a new delete action with given selection and default text
	 * 
	 * @param selectedObject
	 *            the selected object,which cannot be null
	 * 
	 */
	public DeleteAction( Object selectedObject )
	{
		this( selectedObject, DEFAULT_TEXT );
	}
	/**
	 * Create a new delete action with given selection and text
	 * 
	 * @param selectedObject
	 *            the selected object,which cannot be null
	 * @param text
	 *            the text of the action
	 */
	public DeleteAction( Object selectedObject, String text )
	{
		super( selectedObject, text );
		ISharedImages shareImages = PlatformUI.getWorkbench( )
				.getSharedImages( );
		setImageDescriptor( shareImages.getImageDescriptor( ISharedImages.IMG_TOOL_DELETE ) );
		setDisabledImageDescriptor( shareImages.getImageDescriptor( ISharedImages.IMG_TOOL_DELETE_DISABLED ) );
		setAccelerator( SWT.DEL );
	}
	protected boolean doAction( ) throws Exception
	{
		hasExecuted = isOKPressed( getSelection( ) );