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
* Closes the design. The report design handle is no longer valid after
	 * closing the design. This method will send notifications instance of
	 * <code>DisposeEvent</code> to all the dispose listeners registered in
	 * the module.
	 */
	public void close( )
	{
		module.close( );
		DisposeEvent event = new DisposeEvent( module );
		module.broadcastDisposeEvent( event );
	}
	/**
	 * Returns the structures which are defined in report design and all
	 * included valid libraries. This method will filter the structure with
	 * duplicate name with the follow rule.
	 * 
	 * <ul>
	 * <li>The structure defined in design file overrides the one with the same
	 * name in library file.
	 * <li>The structure defined in preceding library overrides the one with
	 * the same name in following library file.
	 * <ul>
	 * 
	 * @param propName
	 *            name of the list property
	 * @param nameMember
	 *            name of the name member
	 * @return the filtered structure list with the above rule.
	 */
	List getFilteredStructureList( String propName, String nameMember )