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How to Cancel Drop Operation from LayoutControlToolBox to LayoutControl


Product Version 2019.3.1023
Product RadLayoutControl for WPF


How to cancel the drop operation from the LayoutControlToolBox to the RadLayoutControl.


To disallow the drop of a particular item from the toolbox to the RadLayoutControl you need to handle the drag and drop events of the DragDropManager and more specifically, the DragOver event.

The example below shows how to cancel the drop of a LayoutControlExpanderGroup but this can also be modified to work for any element.

public MainWindow() 
    DragDropManager.AddDragOverHandler(this.layout, OnLayoutControlDragOver, false); 
private void OnLayoutControlDragOver(object sender, Telerik.Windows.DragDrop.DragEventArgs e) 
    var proxy = (LayoutControlHierarchicalNodeProxy)DragDropPayloadManager.GetDataFromObject(e.Data, "Telerik.Windows.Controls.LayoutControl.LayoutControlHierarchicalNodeProxy"); 
    if (proxy.OriginalItem is LayoutControlExpanderGroup) 
        e.Effects = DragDropEffects.None; 
        e.Handled = true; 

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