Bug 156632 [Acceptance]Cannot paste theme when select Themes in Outline.
Description: Cannot paste theme when select Themes in Outline. Steps to reproduce: 1. New a library. 2. Select defaulttheme in outline and cut it 3. Select Themes and right click to paste the theme back. Expected result: Paste in context menu can be used. Actual result: Paste is gray
UI/org.eclipse.birt.report.designer.core/src/org/eclipse/birt/report/designer/util/DNDUtil.java
{
		content = unwrapToModel( content );
		DesignElementHandle child = null;
		if ( content instanceof SlotHandle )
		{
			child = ( (SlotHandle) content ).getElementHandle( );
		}
		else if ( content instanceof DesignElementHandle )
		{
			child = (DesignElementHandle) content;
		}
		if ( child != null )
		{
			for ( int i = 0; i < handles.length; i++ )
			{
				if ( content == handles[i] )
				{
					continue;
				}
				
				if ( child == handles[i] )
				{
					return true;
				}
				if ( handles[i] instanceof DesignElementHandle )
				{
					
					if ( child instanceof CellHandle
							&& handles[i] instanceof ColumnHandle )
					{