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
* the module. Each in the list is instance of
	 * <code>SharedStyleHandle</code> .If any style selected has a duplicate
	 * name with that of one style already existing in the report design, this
	 * method will rename it and then add it to the design.
	 * 
	 * @param stylesheet
	 *            the style sheet handle that contains all the selected styles
	 * @param selectedStyles
	 *            the selected style list
	 * 
	 * 
	 */
	abstract public void importCssStyles( CssStyleSheetHandle stylesheet,
			List selectedStyles );
	/**
	 * Sets the theme to a report.
	 * 
	 * @param themeName
	 *            the name of the theme
	 * @throws SemanticException
	 */
	public void setThemeName( String themeName ) throws SemanticException
	{
		ThemeCommand command = new ThemeCommand( (Module) getElement( ) );
		command.setTheme( themeName );
	}
	/**
	 * Returns the refresh rate when viewing the report.
	 * 
	 * @return the refresh rate