PowerShell: In einen Job eine Variable auf Script-Ebene ändern

# create form
$form = [System.Windows.Forms.Form]@{
    Text = "Windows Forms Multi-Threading"  
    Size = '450,150'  
}
# create label
$label = [System.Windows.Forms.Label]@{
    Name = 'label1'  
    Location = '10,10'  
    Text = "Click me to start background task"  
    Dock = 'Fill'  
    TextAlign = 'MiddleCenter'  
    Font = [System.Drawing.Font]::new('Calibri',15)  
}

# add click event to the label
$label.add_Click({
    if ($cmd.InvocationStateInfo.State -ne 'Running'){  
        # start background script
        $result = $cmd.BeginInvoke()
    }
})

# event when closing form
$form.add_Closed({
    # end backgound script if it's still running 
    if ($cmd.InvocationStateInfo.State -ne 'Completed'){  
        $cmd.Stop()
    }
    $cmd.Dispose()
})

# create synchronized hashtable for bidirectional communication across threads
$ht = [hashtable]::Synchronized(@{})
# create runspace
$newRunspace =[runspacefactory]::CreateRunspace()
$newRunspace.ApartmentState = "STA"  
$newRunspace.ThreadOptions = "ReuseThread"  
$newRunspace.Open()
# populate the synchronized Hashtable Variable to the runspace (make it available to the script)
$newRunspace.SessionStateProxy.SetVariable("ht",$ht)  
# add the whole form object to the hashtable, so we can access the whole form including it's nested controls 
$ht.Form = $form

# create new powershell process
$cmd = [powershell]::Create()
# define the script to execute in the process
[void]$cmd.AddScript({
    # everything here is executed in another thread
    # example countdown
    3..1 | %{
        # use the created object in the hashtable to change text in the label of the form
        $ht.Form.Controls['label1'].Text = "Background-Task is running, wait $_ seconds ..."  
        sleep 1
    }
    $ht.Form.Controls['label1'].Text = "Finished"  
    sleep 1
    $ht.Form.Controls['label1'].Text = "Click me to start background task"  
})
# assign the runspace to the process
$cmd.Runspace = $newRunspace

# add controls to the form
$form.Controls.AddRange(@($label))
# show form
[void]$form.ShowDialog()