Public Class Form1
 '// [...] Designer
 
    Private Sub t_MouseDown(ByVal sender As Object, ByVal e As _
      System.Windows.Forms.MouseEventArgs)
        CType(sender, TextBox).DoDragDrop(sender, DragDropEffects.Move)
    End Sub
 
    Private Sub t_DragEnter(ByVal sender As Object, ByVal e As _
      System.Windows.Forms.DragEventArgs)
        If (e.Data.GetDataPresent(GetType(TextBox))) Then
            e.Effect = DragDropEffects.Move
        Else
            e.Effect = DragDropEffects.None
        End If
    End Sub
 
    Private Sub t1_DragDrop(ByVal sender As Object, ByVal e As _
      System.Windows.Forms.DragEventArgs)
        CType(sender, TextBox).Text = CType(e.Data.GetData(GetType(TextBox)), _
        TextBox).Text
        CType(e.Data.GetData(GetType(TextBox)), TextBox).Text = String.Empty
    End Sub
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles MyBase.Load
        For Each c As Control In Me.Controls
            If TypeOf (c) Is TextBox Then
                c.AllowDrop = True
                AddHandler c.MouseDown, AddressOf t_MouseDown
                AddHandler c.DragDrop, AddressOf t1_DragDrop
                AddHandler c.DragEnter, AddressOf t_DragEnter
            End If
        Next
    End Sub
End Class