Public Class Form1
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
        MsgBox("Der Text in der TextBox1 ist " & MeasureText(TextBox1.Text, _
        TextBox1.Font).ToString & " Pixel breit")
    End Sub
    Private Function MeasureText(ByVal s As String, ByVal fn As Font) As Int32
        Return TextRenderer.MeasureText(s, fn).Width
    End Function
End Class