TreeGridView AllowDrop or any DragDrop is impossible.

[WileyNg]

In the first GridView example, I could do a dragdrop.

In the second TreeGridView example, I tried to do DragDrop with the rows but turned out selecting them.
I have AllowDrop turned on and I have OnDragEnter watching the DragEnter event. It hasn't been triggered once in the TreeGridView example.
@cwensley May I know what caused this to happen?

Recording.52.mp4

 stackGrid = new TreeGridView
            {
                AllowDrop = true,
                AllowColumnReordering = true,
                AllowEmptySelection = true,
                AllowMultipleSelection = true,
                ShowHeader = true,
                GridLines = GridLines.Both,
                RowHeight = 22,
            };

[cwensley]

A more complete example would be required here. How are you calling DoDragDrop? It should be on a MouseMove event of some sort.

[WileyNg]

I see!!!
Thanks! MouseMove does it!

[WileyNg]

Post my code here if anyone is wondering how this is done.

private void OnMouseDown(object sender, MouseEventArgs e)
        {
            mousedownPoint = e.Location;
        }

        private void OnMouseMove(object sender, MouseEventArgs e)
        {
            if (mousedownPoint == null
                 && !dragging
                 && e.Buttons == MouseButtons.Primary)
            {
                var data = new DataObject();

                Rhino.DocObjects.RhinoObject[] objs = Rhino.RhinoDoc.ActiveDoc.Objects.GetSelectedObjects(false, false).ToArray();
                Display.selectedMeshes = objs.Select(x => new Rhino.DocObjects.ObjRef(x))
                                             .Where(i => i.Mesh() != null)
                                             .ToArray();

                data.SetObject(dragging, dragType_Mesh);
                meshGrid.DoDragDrop(data, DragEffects.Copy);

                Rhino.RhinoDoc.ActiveDoc.Objects.UnselectAll();
                Rhino.RhinoDoc.ActiveDoc.Views.Redraw();
                RhinoApp.SendKeystrokes(" ", true);

                dragging = true;
                e.Handled = true;
                DrawGridView();
            }

            if (!dragging
              && e.Buttons == MouseButtons.Primary
              && mousedownPoint != null
              && mousedownPoint.Value.Distance(e.Location) >= dragOffset)
            {
                var cell = meshGrid.GetCellAt(e.Location);

                if (cell.Item != null)
                {
                    var data = new DataObject();
                    data.SetObject(meshGrid.SelectedRows.ToArray(), dragType);
                    meshGrid.DoDragDrop(data, DragEffects.Move);
                    dragging = true;
                    e.Handled = true;
                }
            }
        }

        private void OnMouseUp(object sender, MouseEventArgs e)
        {
            mousedownPoint = null;
            var grid = (TreeGridView)sender;

            if (grid.SelectedItem == null)
                Rhino.RhinoApp.SetFocusToMainWindow();
        }

        private void OnDragEnter(object sender, DragEventArgs e)
        {
            if (e.Data.Contains(dragType_Mesh))
                e.Effects = DragEffects.Copy;

            if (e.Data.Contains(dragType))
                e.Effects = DragEffects.Move;
        }

        private void OnDragOver(object sender, DragEventArgs e)
        {
            var info = meshGrid.GetDragInfo(e);
            if (info != null && e.Data.Contains(dragType))
            {
                info.RestrictToInsert();
            }
            if (e.Data.Contains(dragType_Mesh))
                info.RestrictToInsert();
        }
        private void OnDragDrop(object sender, DragEventArgs e)
        {

            var info = meshGrid.GetDragInfo(e);
            if (info != null && e.Data.Contains(dragType_Mesh))
            {
                GetElements(info.InsertIndex);
                dragging = false;

            }