Bug 134949 Themes nest in other library
Details: Themes nest in other library Step: 1. Library A use LibraryB, and Library B has a themes 2. Report design use Library A 3. I open the Library tree of A in library explorer and drop the themes from B into layout. Actual result: It pop up an error message and said that the library namespace "B" exists already. Exception result: I don't konw if I can use by this method. But I think it is a method user may be used.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/views/attributes/providers/ChoiceSetFactory.java
*            Choice type key.
	 * @return A String array contains all the allowed values.
	 */
	private static Object[] getUnitChoiceSet( String unitKey )
	{
		ArrayList list = new ArrayList( );
		IChoiceSet choiceSet = DesignEngine.getMetaDataDictionary( )
				.getChoiceSet( unitKey );
		if ( choiceSet != null )
		{
			IChoice[] choices = choiceSet.getChoices( );
			for ( int i = 0; i < choices.length; i++ )
			{
				list.add( choices[i] );
			}
		}
		return list.toArray( new IChoice[0] );
	}
	/**
	 * Gets all the DataSets available.
	 * 
	 * @return A String array contains all the DataSets.
	 */
	public static String[] getDataSets( )
	{
		ArrayList list = new ArrayList( );
		ModuleHandle handle = SessionHandleAdapter.getInstance( )
				.getReportDesignHandle( );
		for ( Iterator iterator = handle.getVisibleDataSets( ).iterator( ); iterator.hasNext( ); )
		{