Adding Double-Click Behavior to Expand/Collapse GanttTask in RadGanttView for WPF

Updated on Sep 15, 2025

Environment

Product	Version
UI for WPF	2023.3.1010

Description

How to add a double-click action that expands/collapses the clicked GanttTask in RadGanttView for WPF.

Solution

Subscribe to the MouseDoubleClick event on the RadGanttView control. Then, in the event handler use the ExpandCollapseService of the GanttView control to expand and collapse items. To get the collapse/expand state of the GanttTask objects, you can use the GetItemWrapperByItemKey of the HierarchicalCollectionAdapter.

C#

	private void RadGanttView_MouseDoubleClick(object sender, MouseButtonEventArgs args)
	{
		var gantt = (RadGanttView)sender;
		var selectedTask = gantt.SelectedItem as GanttTask; 
		if (selectedTask != null && selectedTask.Children.Count > 0)
		{
			HierarchicalItem hierarchicalItem = gantt.ExpandCollapseService.HierarchicalCollectionAdapter.GetItemWrapperByItemKey(selectedTask);
			if (hierarchicalItem != null)
			{
				if (hierarchicalItem.IsExpanded)
				{
					gantt.ExpandCollapseService.CollapseItem(gantt.SelectedItem);
				}
				else
				{
					gantt.ExpandCollapseService.ExpandItem(gantt.SelectedItem);
				}
			}
		}                   
	}