Bug 160429 Drag the datasource and dataset and produce an error gradation in data explorer
Details: Drag the datasource and dataset and produce an error gradation in data explorer Step: 1.New 4 datasource named d1, d2, d3, d4. 2.Drag the datasource in data explorer to change the gradation. (1) Drag d1 between d2 and d3. (2) Drag d2 between d3 and d4. (3) Drag d4 between d2 and d3. (4) Drag d4 to the top. (5) Drag d3 between d1 and d2. (6) Drag d3 to the top. Actual result: (1) d1 will be move to bottom. (2) d2 will be move to bottom. (3) d4 will not be move to anywhere. (4) d4 will not be move to anywhere. (5) d3 will be move to bottom. (6) d3 will be move to bottom. Excepted result: The datasource will be move to the correct station.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/ModuleHandle.java
* Adds a new embedded image.
	 * 
	 * @param image
	 *            the image to add
	 * @throws SemanticException
	 *             if the name is empty, type is invalid, or the same name
	 *             exists.
	 */
	public void addImage( EmbeddedImage image ) throws SemanticException
	{
		PropertyCommand cmd = new PropertyCommand( module, getElement( ) );
		ElementPropertyDefn propDefn = module.getPropertyDefn( IMAGES_PROP );
		cmd.addItem( new CachedMemberRef( propDefn ), image );
	}
	/**
	 * Checks the name of the embedded image in this report. If duplicate, get a
	 * unique name and rename it.
	 * 
	 * @param image
	 *            the embedded image whose name is need to check
	 */
	public void rename( EmbeddedImage image )
	{
		this.module.rename( image );
	}
	/**
	 * Adds all the parameters under the given parameter group to a list.
	 * 
	 * @param list
	 *            the list to which the parameters are added.