Drag From GridView Drop On TextBoxCOntrol

        public RadForm1()
        {
            InitializeComponent();
            RadDragDropService svc =
                this.radGridView1.GridViewElement.GetService<RadDragDropService>();
            svc.PreviewDragStart += svc_PreviewDragStart;
            svc.PreviewDragDrop += svc_PreviewDragDrop;
            svc.PreviewDragOver += svc_PreviewDragOver;
             
            var gridBehavior = this.radGridView1.GridBehavior as BaseGridBehavior;
            gridBehavior.UnregisterBehavior(typeof(GridViewDataRowInfo));
            gridBehavior.RegisterBehavior(typeof(GridViewDataRowInfo), new RowSelectionGridBehavior());
             
            this.radTextBoxControl1.TextBoxElement.AllowDrop = true; 
        }

        //initiates drag and drop service for clicked rows
        public class RowSelectionGridBehavior : GridDataRowBehavior
        {
            protected override bool OnMouseDownLeft(MouseEventArgs e)
            {
                GridDataRowElement row = this.GetRowAtPoint(e.Location) as GridDataRowElement;
                if (row != null)
                {
                    RadGridViewDragDropService svc = this.GridViewElement.GetService<RadGridViewDragDropService>();
                    svc.AllowAutoScrollColumnsWhileDragging = false;
                    svc.AllowAutoScrollRowsWhileDragging = false;
                    svc.Start(row);
                }
                return base.OnMouseDownLeft(e);
            }
        }

        private void svc_PreviewDragDrop(object sender, RadDropEventArgs e)
        {
            RadTextBoxControlElement dropTextBox = e.HitTarget as RadTextBoxControlElement;
            GridDataRowElement draggedRowElement = e.DragInstance as GridDataRowElement;
            if (dropTextBox == null || draggedRowElement == null)
            {
                e.Handled = false;
                return;
            }
            e.Handled = true;
            dropTextBox.Text = draggedRowElement.RowInfo.Cells["ProductName"].Value + "";
        }

        private void svc_PreviewDragOver(object sender, RadDragOverEventArgs e)
        {
            e.CanDrop = e.HitTarget is RadTextBoxControlElement;
        }

        private void svc_PreviewDragStart(object sender, PreviewDragStartEventArgs e)
        {
            e.CanStart = true;
        }