如何防止子控件触发DragEnter事件

Question

I built a custom TreeView in WPF. The control supports Drag&Drop (reordering or nodes and dragging nodes outside the control to other controls).

I have to detect whether the drag & drop operation comes from other controls or is started from within the TreeView. I also want to detect if the drag operation "leaves" the control.

For this detection, I am using the regular DragEnter and DragLeave events. The problem here is, that this event is also being fired for child controls.

I start a drag operation and the DragEnter event is being fired. When I move the mouse over a child control, the DragEnter event is fired again - in my opinion this is the correct behavior, because the child control does not handle the event and is "bubbling" all the way to the main control (outer most control).

Is there any way to prevent this behavior? I tried settings "AllowDrop" for each child control, but this results in a "Forbidden" cursor.

As a workaround, I have implemented code that will set the IsHitTestVisible property for all TreeViewItem instances to False and when the drag operation is stopped, the property is set back to true. Is there a nicer solution?