Bug 167545 Copy a cascading parameter group and paste it to another parameter group causes an exception thrown
Steps to reproduce: 1.Copy a cascading parameter group using short cut key "Ctrl+x"/"Ctrl+c", or choosing context menu "Cut"/"Copy"; 2.Paste it to another parameter group using short cut key "Ctrl+v", or choosing context menu "Paste"; Expected result: The source one is pasted in the destination. Actual result: An exception thrown org.eclipse.birt.report.model.api.command.ContentException: The Cascading Parameter Group("Source") is not allowed in the slot (parameters) of Parameter Group("Destination").
UI/org.eclipse.birt.report.designer.core/src/org/eclipse/birt/report/designer/util/DEUtil.java
* Relativizes the path against this base path.
	 * 
	 * @param basePath
	 *            the base path
	 * @param path
	 *            the path to convert
	 * @return The relative path based on the base path if it is possible, or
	 *         the original path
	 * 
	 */
	public static String getRelativedPath( String basePath, String path )
	{
		File baseFile = new File( basePath );
		if ( baseFile.isFile( ) )
		{
			baseFile = baseFile.getParentFile( );
		}
		return URIUtil.getRelativePath( baseFile.getAbsolutePath( ), path );
	}
	/**
	 * Returns the handle of the action of the given element.
	 * 
	 * @param element
	 *            the element handle
	 * @return the handle of the action, or null if the element is not a proper
	 *         type
	 */
	public static ActionHandle getActionHandle( ReportItemHandle element )
	{
		ActionHandle actionHandle = null;