Private Sub TestToolStripMenuItem_Click(ByVal sender As System.Object, _
      ByVal e As System.EventArgs) Handles ContextMenuStrip1.Click
        Dim contextMenu As ContextMenuStrip = CType(sender, ContextMenuStrip)
        If contextMenu.Tag Is Nothing Then
            Dim frm = New Form2
            frm.Label1.Text = contextMenu.SourceControl.Name.ToString
            contextMenu.Tag = frm
            frm.Tag = contextMenu
            AddHandler frm.FormClosed, AddressOf frm_FormClosed
            frm.Show()
        End If
    End Sub

If contextMenu.Tag Is Nothing Then