Public Class Form1
    Dim Ts As New ToolStrip With {.Parent = Me}
    Dim WithEvents Tmi As New ToolStripMenuItem
 
    Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) _
      Handles MyBase.Load
        Tmi.Text = "Filter"
        For i As Int32 = 0 To 3
            Tmi.DropDownItems.Add(New ToolStripMenuItem With {.Text = "Filter" _
              & i.ToString, .CheckOnClick = True})
        Next
        Ts.Items.Add(Tmi)
    End Sub
 
    Private Sub Mi_ItemClicked(sender As Object, e As _
      ToolStripItemClickedEventArgs) Handles Tmi.DropDownItemClicked
        Dim Ci = CType(e.ClickedItem, ToolStripMenuItem)
        For Each Itm As ToolStripMenuItem In Tmi.DropDownItems
            If Not Itm Is Ci Then
                Itm.Enabled = Not Itm.Enabled
            End If
        Next
    End Sub
End Class