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
this.insertType = type;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.gef.ui.actions.WorkbenchPartAction#calculateEnabled()
	 */
	protected boolean calculateEnabled( )
	{
		slotHandle = getDefaultSlotHandle( insertType );
		return DNDUtil.handleValidateTargetCanContainType( slotHandle,
				insertType )
				&& DNDUtil.handleValidateTargetCanContainMore( slotHandle, 0 );
	}
	/**
	 * Returns the container slotHandle.
	 *  
	 */
	private SlotHandle getDefaultSlotHandle( String insertType )
	{
		IStructuredSelection models = InsertInLayoutUtil.editPart2Model( getSelection( ) );
		if ( models.isEmpty( ) )
		{
			return null;
		}
		model = models.getFirstElement( );
		if ( model instanceof SlotHandle )
		{
			return (SlotHandle) model;
		}