I have a form behavior I didn't expect.

Create a new windows application project.

add a windows form form2
in the activated event change the background color
Private Sub Form2_Activated(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Activated
Me.BackColor = Color.Red
End Sub

Change form1 to ismdicontainer = true
add a menu to form1
in the click of the menupad instantiate form2
Private Sub MenuItem2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MenuItem2.Click
Dim ThisForm As New Form2()
ThisForm.MdiParent = Me
ThisForm.Show()

End Sub

run the application
click on the menu
form2 appears and the background is red
click on the menu again
another form2 appears but the background color does not change. The activated event does not fire.

WHY???????????????