Bug 123726 "Top n", "Bottom n" in highlight dialog doesn't work.
Description: "Top n", "Bottom n" in highlight dialog doesn't work. Steps to reproduce: 1. Add a highlight for a table. 2. Set highlight rule: "account_id", "top n", "3", let its font color red. 3. Preview the report, it doesn't work. Attached is design file.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/PreparedQuery.java
prepareExpressions( trans.getBeforeExpressions(), groupLevel, false, cx );
		prepareExpressions( trans.getRowExpressions(), groupLevel, false, cx );
		
		
		Collection subQueries = trans.getSubqueries( );
		Iterator subIt = subQueries.iterator( );
		while ( subIt.hasNext( ) )
		{
			ISubqueryDefinition subquery = (ISubqueryDefinition) subIt.next( );
			PreparedSubquery pq = new PreparedSubquery( subquery, this, groupLevel );
			subQueryMap.put( subquery.getName(), pq);
		}
	}
	
	/**
	 * Prepares all expressions in the given collection
	 * 
	 * @param expressions
	 * @param groupLevel
	 * @param afterGroup
	 * @param cx
	 */
	private void prepareExpressions( Collection expressions, int groupLevel,
			boolean afterGroup, Context cx )
	{
	    if ( expressions == null )
	        return;
	    
	    AggregateRegistry reg = this.aggrTable.getAggrRegistry( groupLevel, afterGroup, cx );
	    Iterator it = expressions.iterator();