Bug 151959 inappropriate screen operation
steps to reproduce: - create a report - add a grid item (3x3) - switch to Outline view - expand the grid item to see its rows and cells - select the grid item, and drag it into any of its own cell expected behavior: - is it an invalid screen operation? if it is, it should be banned actual behavior: - the grid item was disappeared surprisingly
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/DesignElement.java
return false;
		
		DesignElement containerObj = this;
		int slot = slotID;
		while ( containerObj != null )
		{
			ElementDefn defn = (ElementDefn) containerObj.getDefn( );
			SlotDefn slotInfo = (SlotDefn) defn.getSlot( slot );
			if ( slotInfo != null && !slotInfo.isManagedByNameSpace( ) )
				return false;
			slot = containerObj.getContainerSlot( );
			containerObj = containerObj.getContainer( );
		}
		return true;
	}
	/**
	 * Determines whether this element is managed by namespace. If this element
	 * is a pending node or the container is not managed by the namespace,
	 * return false. Otherwise true.
	 * 
	 * @return true if this element is managed by namespace, otherwise false
	 */
	public boolean isManagedByNameSpace( )
	{
		if ( getContainer( ) == null )
			return false;
		return getContainer( ).isManagedByNameSpace( getContainerSlot( ) );
	}
	/**
	 * Determines if the current element can be transformed to a template