Private Sub dgv_Mousemove(sender As Object, _
        e As MouseEventArgs) Handles dgv.MouseMove
 
        With dgv
            Dim info As DataGridView.HitTestInfo = .HitTest(e.X, e.Y)
            If info.RowIndex <> -1 AndAlso info.ColumnIndex <> -1 Then
                If .Columns(info.ColumnIndex).ValueType = GetType(String) Then
 
                    Dim value As [Object] = _
                    .Rows(info.RowIndex).Cells(info.ColumnIndex).Value
 
                    If Not value Is Nothing AndAlso _
                       Not IsDBNull(value) AndAlso _
                       Not String.IsNullOrEmpty(value.ToString) Then
                        .DoDragDrop(value, DragDropEffects.Copy)
                    End If
                End If
            End If
        End With
    End Sub

    Private Sub tbo_DragDrop(sender As Object, _
    e As System.Windows.Forms.DragEventArgs) Handles tbo.DragDrop
 
        If (e.AllowedEffect And DragDropEffects.Copy) = _
            DragDropEffects.Copy Then
            tbo.Text = e.Data.GetData(GetType(String)).ToString
        End If
 
    End Sub
 
    Private Sub tbo_DragOver(sender As Object, _
        e As System.Windows.Forms.DragEventArgs) Handles tbo.DragOver
 
        If Not (e.Data.GetDataPresent(GetType(System.String))) Then
            e.Effect = DragDropEffects.None
        Else
            If (e.AllowedEffect And DragDropEffects.Copy) = _
                DragDropEffects.Copy Then
                e.Effect = DragDropEffects.Copy
            Else
                e.Effect = DragDropEffects.None
            End If
        End If
    End Sub