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
* @return A handle for working with the components.
	 */
	public SlotHandle getComponents( )
	{
		return getSlot( COMPONENT_SLOT );
	}
	/**
	 * Returns the name of the tool that created the design.
	 * 
	 * @return the name of the tool
	 */
	public String getCreatedBy( )
	{
		return getStringProperty( CREATED_BY_PROP );
	}
	/**
	 * Returns a slot handle to work with the data sets within the report. Note
	 * that the order of the data sets within the slot is unimportant.
	 * 
	 * @return A handle for working with the data sets.
	 */
	public SlotHandle getDataSets( )
	{
		return getSlot( DATA_SET_SLOT );
	}
	/**
	 * Returns a slot handle to work with the data sources within the report.
	 * Note that the order of the data sources within the slot is unimportant.
	 * 
	 * @return A handle for working with the data sources.