Private Sub DataGridView1_EditingControlShowing1(sender As Object, e As _
  DataGridViewEditingControlShowingEventArgs) Handles _
  DataGridView1.EditingControlShowing
        If DataGridView1.CurrentCell.ColumnIndex <> _
        DataSet1.DtDaten.DateianhangColumn.Ordinal Then
            Return
        End If
 
        Dim btn As New Button
        With btn
            .Dock = DockStyle.Right
            .Name = "btnOpen"
            .Text = "..."
            .Width = 25
        End With
 
        If Not DataGridView1.EditingPanel.Controls.ContainsKey(btn.Name) Then
            DataGridView1.EditingPanel.Controls.Add(btn)
        End If
        AddHandler btn.Click, AddressOf btn_Click
        btn.BringToFront()
    End Sub
 
    Private Sub btn_Click(sender As Object, e As EventArgs)
        MessageBox.Show("Ereignis")
    End Sub