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 e = this;
		while ( e != null )
		{
			if ( e == element )
				return true;
			e = e.getExtendsElement( );
		}
		return false;
	}
	/**
	 * Determines if any elements extend this element.
	 * 
	 * @return True if the element is extended, false if not.
	 */
	public boolean hasDerived( )
	{
		return derived != null && derived.size( ) > 0;
	}
	/**
	 * Returns the optional display name. Note: set the display name by calling
	 * the {@link #setProperty( String, Object )}method.
	 * <p>
	 * Part of: The name system.
	 * 
	 * @return Returns the displayName.
	 */
	public String getDisplayName( )
	{
		return (String) getLocalProperty( null, DISPLAY_NAME_PROP );
	}