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
for ( int i = 0; i < valueList.size( ); i++ )
		{
			
			ElementRefValue item = (ElementRefValue) valueList.get( i );
			resolveElementReference( module, prop, item );
		}
		return valueList;
	}
	/**
	 * Resolves a property element reference. The reference is the value of a
	 * property of type property element reference.
	 * 
	 * @param module
	 *            the module information needed for the check, and records any
	 *            errors
	 * @param prop
	 *            the property whose type is element reference
	 * @param value
	 *            the element reference value to resolve
	 * @return the element reference value is always returned, which contains
	 *         the information of element resolution.
	 */
	public ElementRefValue resolveElementReference( Module module,
			ElementPropertyDefn prop, ElementRefValue value )
	{
		if ( value == null || module == null )
			return (ElementRefValue) value;
		ElementRefValue ref = (ElementRefValue) value;
		if ( ref.isResolved( ) )
			return ref;