GridView for ASP.NET Web Forms generates client-side script that allows users to collapse and expand the groups without round trips to the server.

If you set the OutlineMode property to StartCollapsed or StartExpanded, the grid will display expanded/collapsed icons next to each group header row. The users can click these icons to collapse and expand the groups to see the overall structure or the details of the data.

The behavior for the outline nodes is as follows:

• Click:
• • If the node is currently expanded, it becomes collapsed. All subordinate group headers and data are hidden.
  • If the node is currently collapsed, it becomes expanded. If there are any subordinate group headers, they are displayed in the collapsed state. If there are no subordinate group headers, the data is displayed.
• SHIFT-Click:
• • All nodes and data below the node that was clicked are displayed.

You can select different icons for the group headers using the CollapsedImageClass and ExpandedImageClass properties.

For additional information on grouping, see the GridView for ASP.NET Web Forms Task-Based Help.