Bug 176107 row.__rownum cannot be directly used as group key
Create a table that bind it to a data set. Insert a group. For the Group On field, click on the "..." button to edit the expression, and select from "Availble Column Bindings" | "Table" | "RowNum". This creates a Group On Expression "row.__rownum". The resulting report design cannot be run. It produces error: Column binding "row.__rownum" does not exist. To workaround this, one must create another binding on the table and set its expression to "row.__rownum", then use the new binding as group key. This should not have been necessary. The "__rownum" binding should be implicitly available in all contexts that have a data set. E.g., it should be usable directly as group key, sort key, and in conditional format expressions, etc. Attached is a sample report that produces the error.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/expression/ExpressionCompilerUtil.java
String oprand2 = getExprText(((IConditionalExpression)expression).getOperand2( ));
			return ExpressionUtil.hasAggregation(  expr )
				   ||ExpressionUtil.hasAggregation(  oprand1 )
				   ||ExpressionUtil.hasAggregation( oprand2 );
		}
		
		return false;
	}
	/**
	 * Check whether filter in query contains aggregation. If aggregation is
	 * TOPN,BOTTOMN,TOPPERCENT,BOTTMEPERCENT return true. else return false;
	 * 
	 * @return
	 */
	public static boolean isValidExpressionInQueryFilter(
			IBaseExpression expression )
	{
		if ( expression instanceof IScriptExpression )
		{
			String text = ( (IScriptExpression) expression ).getText( );
			Context context = Context.enter( );
			
			AggregateRegistry aggrReg = new AggregateRegistry( ) {
				public int register( AggregateExpression aggregationExpr )
				{
					return -1;
				}
			};
			try
			{