Private Sub DisableEnable()
        Dim myCheck As ToolStripMenuItem
        For Each myCheck In mnuFilter.DropDownItems
            If myCheck.Checked AndAlso myCheck.Enabled Then
                Return
            Else
                myCheck.Checked = False
                myCheck.Enabled = False
            End If
        Next
    End Sub

Public Sub Autobahn(ByVal Regen As Boolean)
If Regen Then
MessageBox.Show("SOFORT LICHT EINSCHALTEN!!!", "Achtung es regnet!", MessageBoxButtons.OK, MessageBoxIcon.Warning)
End If
End Sub

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

Public Sub Autobahn(ByVal Regen As Boolean)
If Regen Then
MessageBox.Show("SOFORT LICHT EINSCHALTEN!!!", "Achtung es regnet!", MessageBoxButtons.OK, MessageBoxIcon.Warning)
End If
End Sub