PowerShell WPF popup in lower right corner of the screen

lowerright.ps1

[xml]$xaml =  '<Window
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
		WindowStyle="None" ResizeMode="NoResize" ShowInTaskbar="False"
        Height="0" Width="0" Background="Transparent"> 
	 <Popup Name="popup" Placement="AbsolutePoint" StaysOpen="False">
		 <Grid Name="grid" Height="400" Width="390" Background="DarkGray">
			<Label Name="label" Content="Double-click to close" Foreground="White" FontSize="18"/>
		</Grid>
	</Popup>
</Window>'
			
try { Add-Type -AssemblyName PresentationFramework,System.Windows.Forms} 
catch { throw "Failed to load Windows Presentation Framework assemblies." }

$script:form = [Windows.Markup.XamlReader]::Load((New-Object System.Xml.XmlNodeReader $xaml))
$xaml.SelectNodes("//*[@Name]") | ForEach-Object { Set-Variable -Name ($_.Name) -Value $form.FindName($_.Name) -Scope Script }

$screen = [Windows.Forms.Screen]::PrimaryScreen.WorkingArea
$popup.VerticalOffset=$screen.height
$popup.HorizontalOffset=$screen.width

$popup.Add_Loaded({$popup.IsOpen=$true})

$form.Add_MouseDoubleClick({
	$popup.IsOpen = $false
	[void]$form.Close()
})
			
[void]$form.ShowDialog()