Bug 189706 Enhance computed column aggregation function handling in UI.
Due to the issue discussed in 189705, current computed column aggregation builder in data set editor has bugs to extend: 1.When new a computed column, the aggregation argument field cannot be correctly set. 2.The argument field cannot be correct grayed out when user select a aggregation function without arguments 3.The available aggregation function list is incomprehensive 4.Some aggregation function cannot be set to model(say, weightedAve).
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/executor/transform/pass/DataSetProcessUtil.java
}
	/**
	 * 
	 * @return
	 * @throws DataException
	 */
	private void populateComputedColumns( List aggCCList ) throws DataException
	{
		if ( !psController.needDoOperation( PassStatusController.DATA_SET_COMPUTED_COLUMN_POPULATING ) )
			return;
		
		if ( !psController.needDoOperation( PassStatusController.DATA_SET_FILTERING ) )
		{
			if ( iccState != null )
			{
				for ( int i = 0; i < iccState.getCount( ); i++ )
				{
					if ( iccState.isValueAvailable( i ) )
					{
						for ( int k = 0; k < this.populator.getQuery( )
								.getFetchEvents( )
								.size( ); k++ )
						{
							if ( this.populator.getQuery( )
									.getFetchEvents( )
									.get( k ) instanceof ComputedColumnHelper )
							{
								ComputedColumnHelper helper = (ComputedColumnHelper) this.populator.getQuery( )
										.getFetchEvents( )
										.get( k );