Public Class Form1
    Dim WithEvents Bt1 As New Button With {.Dock = DockStyle.Bottom, .Text = _
      "Rechner1", .Parent = Me}
    Dim WithEvents Bt2 As New Button With {.Dock = DockStyle.Bottom, .Text = _
    "Rechner2", .Parent = Me}
    Dim WithEvents p1, p2 As Process
 
    Private Sub Bt1_MouseDown(sender As Object, e As MouseEventArgs) Handles _
      Bt1.MouseDown
        Bt1.BackColor = Color.Green
        Bt1.Enabled = False
        p1 = Process.Start("calc")
        p1.EnableRaisingEvents = True
    End Sub
 
    Private Sub Bt2_MouseDown(sender As Object, e As MouseEventArgs) Handles _
      Bt2.MouseDown
        Bt2.BackColor = Color.Green
        Bt2.Enabled = False
        p2 = Process.Start("calc")
        p2.EnableRaisingEvents = True
    End Sub
 
    Private Sub p1_Exited(ByVal sender As Object, ByVal e As EventArgs) Handles _
      p1.Exited
        Bt1.BackColor = SystemColors.Control
        Me.Invoke(Sub() Bt1.Enabled = True)
    End Sub
 
    Private Sub p2_Exited(ByVal sender As Object, ByVal e As EventArgs) Handles _
      p2.Exited
        Bt2.BackColor = SystemColors.Control
        Me.Invoke(Sub() Bt2.Enabled = True)
    End Sub
End Class