There's no buil-in selection capability for summary rows. You could probably implement this yourself, though. What you would have to do is trap the MouseUp event of the grid and use the UIElements to determine if a summary was clicked on and if so, which one. Then you could use the Appearance on the SummarySettings to change the BackColor and ForeColor and make it look selected. You would probably want to keep a list somewhere of which summaries are selected, so that when the summary is clicked you know whether to select or de-select it. 

Overall, it's probably not that difficult.