Changing Group Sort at runtime "!"

The group band syntax has this nice little property which is set in the DWO painter on the Group Header property sheet

group(level=1 header.height=0 ..... trailer.gradient.spread="100" sort="report_name A " )

Requirement is to change the group sort value at runtime to support column header click sorting when the detail band is collapsed and only group 1 band is visible

Funny but there is no online help for the group.x.sort property.

messagebox('value', describe( 'datawindow.header.1.sort' ) )

//returns ! == If the property list contains an invalid item, Describe returns an exclamation point for that item

Of course modify returns a syntax error too!

Changing the Table.Sort property is not useful in this case, as I need to sort groups not rows

Of course SetSort( ) and Sort( ) are equally not useful in this case

Short of a multi DWO solution or changing to SQL grouping. Am I missing something?

TIA

Yakov