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
*/
	public void gatherDescendents( ArrayList list )
	{
		if ( derived == null )
			return;
		for ( int i = 0; i < derived.size( ); i++ )
		{
			DesignElement child = (DesignElement) derived.get( i );
			list.add( child );
			child.gatherDescendents( list );
		}
	}
	/**
	 * Checks if the element has defined any user properties. Checks only this
	 * element, not its parents.
	 * 
	 * @return True if the element has user properties, false if not.
	 */
	public boolean hasUserProperties( )
	{
		return userProperties != null && !userProperties.isEmpty( );
	}
	/**
	 * Checks if this element has any locally-defined property values.
	 * 
	 * @return True if the element has property values, false if not.
	 */
	public boolean hasLocalPropertyValues( )
	{
		return !propValues.isEmpty( );