Bug 122212 Cancel the action of creating a chart, then delete a data set, it still refers to the non-existent chart.
Description: Cancel the action of creating a chart, then delete a data set, it still refers to the non-existent chart. Steps to reproduce: 1. Create a data source and related data set. 2. Add a chart and select a data set in chart dialog. 3. Cancel creating chart action. 4. Delete the data set from data explorer view. 5. It pops up a dialog said that "the data set refers to the chart". But indeed the chart doesn't exist.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/actions/BaseInsertMenuAction.java
else if ( model instanceof DesignElementHandle )
		{
			DesignElementHandle handle = (DesignElementHandle) model;
			if ( handle.getDefn( ).isContainer( ) )
			{
				int slotId = DEUtil.getDefaultSlotID( handle );
				if ( handle.canContain( slotId, insertType ) )
				{
					return handle.getSlot( slotId );
				}
			}
			return handle.getContainerSlotHandle( );
		}
		return null;
	}
	protected Request insertElement( ) throws Exception
	{
		Request request = new Request( IRequestConstants.REQUEST_TYPE_INSERT );
		Map extendsData = new HashMap( );
		extendsData.put( IRequestConstants.REQUEST_KEY_INSERT_SLOT, slotHandle );
		extendsData.put( IRequestConstants.REQUEST_KEY_INSERT_TYPE, insertType );
		extendsData.put( IRequestConstants.REQUEST_KEY_INSERT_POSITION,
				InsertAction.BELOW );
		request.setExtendedData( extendsData );
		ProviderFactory.createProvider( slotHandle.getElementHandle( ) )
				.performRequest( model, request );
		return request;
	}
	protected void selectElement( final Object element, final boolean edit )
	{