Hello Martin,

You have a point here. After a brief discussion with the development team regarding your scenario, we can agree that this behavior could be improved. It is not expected for the target node to expand when the drag-drop operation is canceled. Therefore I have changed the status of the feedback item. As a workaround, you may consider using the NodeExpandedChanging event handler to cancel the expand operation.

Your account has been credited with Telerik Points as a token of appreciation for bringing this to our attention.

Regards,
Dinko | Tech Support Engineer
Progress Telerik

Hello Martin,

This is the default behavior. When a dragged node is dragged over a collapsed node, it will automatically expand. To suppress this, you can subscribe to the NodeExpandedChanging event and cancel the node expanding. You can raise a flag in the DragEnding event handler. Check the following code snippet. You can also check the last section in the Cancel a Drag and Drop Operation help article.

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
        this.radTreeView1.TreeViewElement.ExpandTimerInterval = 5000;
        this.radTreeView1.DragEnding += RadTreeView1_DragEnding;
        this.radTreeView1.NodeExpandedChanging += RadTreeView1_NodeExpandedChanging;
    }

    private void RadTreeView1_NodeExpandedChanging(object sender, Telerik.WinControls.UI.RadTreeViewCancelEventArgs e)
    {
        Debug.WriteLine(radTreeView1.TreeViewElement.DragDropService.State);
        e.Cancel = cancelExpand;       
    }

    bool cancelExpand = false;
    private void RadTreeView1_DragEnding(object sender, Telerik.WinControls.UI.RadTreeViewDragCancelEventArgs e)
    {
        e.Cancel = cancelExpand = true;
    }
}

Regards,
Dinko | Tech Support Engineer
Progress Telerik