Doevents in WPF for Powershell

Add-Type -AssemblyName PresentationFramework
[xml]$Form = @"
    <Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        Title="MainWindow" Height="150" Width="325">
    <Grid>
        <TextBlock Name="TextBlock" Text="0" HorizontalAlignment="Center"/>
        <Button Name="button_Do" Height="35" Width="120" Content="Do"/>
    </Grid>
</Window>
"@

Function DoEvents()
{
    $frame = New-Object System.Windows.Threading.DispatcherFrame
    [System.Windows.Threading.DispatcherOperationCallback]$CallBack = { $frame.Continue = $false }
    $CurrentDispatcher = [System.Windows.Threading.Dispatcher]::CurrentDispatcher
    $CurrentDispatcher.BeginInvoke("Background", $CallBack, $null)
    [System.Windows.Threading.Dispatcher]::PushFrame($frame)
}

$Reader = (New-Object System.Xml.XmlNodeReader $Form)
$Window = [Windows.Markup.XamlReader]::Load($Reader)

$TextBlock = $Window.FindName("TextBlock")
$button_Do = $Window.FindName("button_Do")
$button_Do.Add_Click({
    for ($i=1; $i -le 5; $i++)
    {
        $window.Title = $i
        $TextBlock.text = $i
        DoEvents
        #[System.Windows.Threading.Dispatcher]::CurrentDispatcher.Invoke("Background", [action]{ })
        #$Window.Dispatcher.Invoke("Background", [action]{})
        Start-sleep 1
    }
})

$Window.ShowDialog()