Public Class Form1

    Private Sub btnStart_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStart.Click
        lstOutput.Items.Clear()
        lstOutput.Items.Add("A: btnStart_Click")
        proc1()
        lstOutput.Items.Add("B: btnStart_Click")

        lstOutput.Items.Add("")
        proc3()
        lstOutput.Items.Add("C: btnStart_Click")
    End Sub

    Sub proc1()
        lstOutput.Items.Add("D: proc1")
        proc2()
        lstOutput.Items.Add("E: proc1")
    End Sub

    Sub proc2()
        lstOutput.Items.Add("F: proc2")
    End Sub

    Sub proc3()
        lstOutput.Items.Add("G: proc3")
        proc2()
        lstOutput.Items.Add("H: proc3")
        proc1()
        lstOutput.Items.Add("I: proc3")
    End Sub

End Class