Prevent Drag on a specific TTreeNode in a TTreeView?

Question

With a TTreeView setup with DragMode dmAutomatic I can use the OnDragDrop and OnDragOver events to handle the drag/drop. But I don't want a particular TTreeNode in the tree to be able to be dragged. I would guess I would need to use dmManual but I haven't found an example of how to do that and wonder if that is what is required?

So the basic question is, how do you prevent a particular TTreeNode item from being able to be dragged (it can be a drop target)? If dmManual, how do you use that mode?

TIA!!

Answer 1

If you want fully exclude drag start, you have to use dmManual mode, as you wrote, and set BeginDrag in OnMouseDown:

if (Button = mbLeft) and 
   (Treeview1.Selected <> nil) and 
   (Treeview1.Selected.Text > 'b') then
        TreeView1.BeginDrag(True);

In this example node with text='aa' is not dragged, while node 'cc' is.

Perhaps sometimes you'll need also change Immediate to False and apply Threshold value (if you need clicks)