Powershell ListBox mit Trennstrich oder Text (Nachfrage)

$x = @()

[void] [System.Reflection.Assembly]::LoadWithPartialName("System.Windows.Forms")  
[void] [System.Reflection.Assembly]::LoadWithPartialName("System.Drawing")   

$objForm = New-Object System.Windows.Forms.Form 
$objForm.Text = "Data Entry Form"  
$objForm.Size = New-Object System.Drawing.Size(300,200) 
$objForm.StartPosition = "CenterScreen"  

$objForm.KeyPreview = $True

$objForm.Add_KeyDown({
    if ($_.KeyCode -eq "Enter") {  
        $script:x = $objcombobox.SelectedItems
        $objForm.Close()
    }
})

$objForm.Add_KeyDown({if ($_.KeyCode -eq "Escape")   
    {$objForm.Close()}})

$OKButton = New-Object System.Windows.Forms.Button
$OKButton.Location = New-Object System.Drawing.Size(75,120)
$OKButton.Size = New-Object System.Drawing.Size(75,23)
$OKButton.Text = "OK"  

$OKButton.Add_Click(
   {
       $script:x = $objcombobox.SelectedItems
       $objForm.Close()
   })

$objForm.Controls.Add($OKButton)

$CancelButton = New-Object System.Windows.Forms.Button
$CancelButton.Location = New-Object System.Drawing.Size(150,120)
$CancelButton.Size = New-Object System.Drawing.Size(75,23)
$CancelButton.Text = "Cancel"  
$CancelButton.Add_Click({$objForm.Close()})
$objForm.Controls.Add($CancelButton)

$objLabel = New-Object System.Windows.Forms.Label
$objLabel.Location = New-Object System.Drawing.Size(10,20) 
$objLabel.Size = New-Object System.Drawing.Size(280,20) 
$objLabel.Text = "Please make a selection from the list below:"  
$objForm.Controls.Add($objLabel) 

$objcombobox = New-Object System.Windows.Forms.ComboBox 
$objcombobox.Location = New-Object System.Drawing.Size(10,40) 
$objcombobox.Size = New-Object System.Drawing.Size(260,20) 

$objcombobox.SelectionMode = "MultiExtended"  

$trennstriche = @('----------Test-Eintrag----------','','Test2')  

$objcombobox.Items.AddRange(@(
"Item 1"  
"Item 2"  
"Item 3"  
$trennstriche
"Item 4"  
"Item 5"  
$trennstriche
"Item 6"  
$trennstriche[1]
"Item 7"  
$trennstriche
"Item 8"  
$trennstriche[2]
"Item 9"  
))

$objcombobox.Height = 70

$objcombobox.add_SelectedIndexChanged({
   $objcombobox.SelectedIndices | ?{$objcombobox.GetSelected($_) -and $objcombobox.Items[$_] -in $trennstriche} | %{$objcombobox.SetSelected($_,$false)}
})

$objForm.Controls.Add($objcombobox) 
$objForm.Topmost = $True

$objForm.Add_Shown({$objForm.Activate()})
[void] $objForm.ShowDialog()

$x