Bug 188829 Move the item ,the trans of the model don't close.
1:New report design. 2:Add a Embedded image. 3:Add another imge , then drag the second imge to the first position. 4:Change the size of the first image. Expected: Image change the size. Now: Image size don't change.
model/org.eclipse.birt.report.model.tests/test/org/eclipse/birt/report/model/command/ContentCommandTest.java
MyContentListener contentListener = new MyContentListener( );
		dataSet.addListener( contentListener );
		
		
		
		
		designHandle.getDataSets( ).drop( dataSet );
		
		assertEquals( MyContentListener.NA, contentListener.recieveChangeEvent );
		
		assertTrue( contentListener.event instanceof ElementDeletedEvent );
		dataSet.removeListener( contentListener );
		contentListener = new MyContentListener( );
		designHandle.getDataSets( ).add( dataSet );
		designHandle.getDataSources( ).drop( dataSource );
		dataSet.addListener( contentListener );
		designHandle.getDataSets( ).drop( dataSet );
		
		
		assertEquals( MyContentListener.NA, contentListener.recieveChangeEvent );
		
		assertTrue( contentListener.event instanceof ElementDeletedEvent );
	}
	/**
	 * Test cases:
	 * 
	 * 1. If add an compound element to the design tree, names of nest elements
	 * should also be added into the name space. This method creates new
	 * elements by using class in elements package.
	 *