This example demonstrates how to implement select/unselect for all rows in a group row.
First, place ASPxCheckBox and ASPxLabel into the ASPxGridLookup.GridViewProperties.Templates.GroupRowContent template.
Second, set the ASPxCheckBox.Checked property and the client-side ASPxCheckBox.ClientSideEvents.CheckedChanged event in the ASPxCheckBox.Load event handler.
In this example the ASPxLabel.Text is bound in the markup using Two-Way DataBinding.
See also
How to implement select/unselect for all rows in a group row
