PROJECT DESCRIPTION
Code Library sample describing how to expand one item at a time in RadGrid when the HierarchyLoadMode property is set to Client.
Since the client load mode will render both the Master and Detail tables, expanding an item will fire the client events such as OnHierarchyExpanding, OnHierarchyExpanded, OnHierarchyCollapsing and OnHierarchyCollapsed.
SOLUTION
To ensure that there is only one item expanded at a time, we will use the OnHierarchyExpanding client event to iterate through all the grid items on the current page and collapse them all if they are expanded.
Markup
JavaScript - hierarchyExpanding event handler