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
DesignElement cur = this;
		while ( cur != null )
		{
			DesignElement extendsElement = cur.getExtendsElement( );
			if ( extendsElement != null )
			{
				parent = extendsElement;
				break;
			}
			cur = cur.getContainer( );
		}
		
		if ( parent == null )
			return null;
		assert parent.getContainer( ) instanceof Module;
		return parent.getRoot( ).getElementByID( baseId );
	}
	/**
	 * Gets a property value given its internal name. This version does the full
	 * property search as defined by the given derived component. That is, it
	 * gets the "effective" property value. The name can be a built-in property
	 * name or a user-defined property name. However, if the name is not valid,
	 * the method will simply return a null property value.
	 * <p>
	 * The search won't search up the inheritance hierarchy if the property is
	 * defined to not inherit.
	 * <p>
	 * Part of: Property value system.
	 * 
	 * @param module