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
else if ( MasterPageHandle.ORIENTATION_PROP.equals( property ) )
		{
			unitKey = DesignChoiceConstants.CHOICE_PAGE_ORIENTATION;
		}
		else if ( MasterPageHandle.TYPE_PROP.equals( property ) )
		{
			unitKey = DesignChoiceConstants.CHOICE_PAGE_SIZE;
		}
		else if ( GroupHandle.INTERVAL_PROP.equals( property ) )
		{
			unitKey = DesignChoiceConstants.CHOICE_INTERVAL;
		}
		else if ( StyleHandle.PAGE_BREAK_BEFORE_PROP.equals( property ) )
		{
			unitKey = DesignChoiceConstants.CHOICE_PAGE_BREAK_BEFORE;
		}
		else if ( StyleHandle.PAGE_BREAK_AFTER_PROP.equals( property ) )
		{
			unitKey = DesignChoiceConstants.CHOICE_PAGE_BREAK_AFTER;
		}
		else if ( StyleHandle.PAGE_BREAK_INSIDE_PROP.equals( property ) )
		{
			unitKey = DesignChoiceConstants.CHOICE_PAGE_BREAK_INSIDE;
		}
		return DesignEngine.getMetaDataDictionary( ).getChoiceSet( unitKey );
	}
	/**
	 * Gets the collection that given property value can selected from them.
	 * 
	 * @param elementName