Hi,

It is indeed bound to diagram's AllowDrop. You could remove the binding by calling System.Windows.Data.BindingOperations.ClearBinding, or just process the node from diagram's own events:

void OnDiagramDragOver(object sender, DragEventArgs e)
{
    var position = e.GetPosition(diagram.DocumentPlane);
    var node = diagram.GetNodeAt(position);
    if (node == thatSpecificNode)
        e.Effects = DragDropEffects.Copy;
    else
        e.Effects = DragDropEffects.None;
    e.Handled = true;
}

void OnDiagramDrop(object sender, DragEventArgs e)
{
    var position = e.GetPosition(diagram.DocumentPlane);
    var node = diagram.GetNodeAt(position);
    if (node == thatSpecificNode)
    {
        e.Effects = DragDropEffects.Copy;
        node.Text = (string)e.Data.GetData(typeof(string));
    }
    e.Handled = true;
} 

Regards,
Slavcho
Mindfusion

It's bound mostly to let the diagram receive these drag and drop events at any position once you enable its own property, otherwise nodes with disabled AllowDrop prevent it. We can't think of adverse effects from unbinding the node if you don't care about handling drag and drop for the whole diagram. The binding is created when node is added as diagram's child element, e.g. try clearing from ItemAdded or NodeCreated event handler.

Regards,
Slavcho
Mindfusion