Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles MyBase.Load
        Dim f As New Form
        f.TopLevel = False
        f.Size = New Size(100, 100)
        Me.Controls.Add(f)
        f.Show()
        AddHandler f.Click, AddressOf foo
    End Sub
 
    Sub foo(ByVal sender As Object, ByVal e As EventArgs)
        MsgBox("form clicked")
    End Sub