$xaml = @" <Window  xmlns='http://schemas.microsoft.com/winfx/2006/xaml/presentation'>  <Border BorderThickness="20" BorderBrush="Yellow" CornerRadius="9" Background='Red'>   <StackPanel>    <Label FontSize="50" FontFamily='Stencil' Background='Red' Foreground='White' BorderThickness='0'>     System will be rebooted in 15 minutes!    </Label>    <Label HorizontalAlignment="Center" FontSize="15" FontFamily='Consolas' Background='Red' Foreground='White' BorderThickness='0'>     Worried about losing data? Talk to your friendly help desk representative and freely share your concerns!    </Label>   </StackPanel>  </Border> </Window> "@ $reader = [System.XML.XMLReader]::Create([System.IO.StringReader] $xaml) $window = [System.Windows.Markup.XAMLReader]::Load($reader) $Window.AllowsTransparency = $True $window.SizeToContent = 'WidthAndHeight' $window.ResizeMode = 'NoResize' $Window.Opacity = .7 $window.Topmost = $true $window.WindowStartupLocation = 'CenterScreen' $window.WindowStyle = 'None' # show message for 5 seconds: $null = $window.Show() Start-Sleep -Seconds 5 $window.Close()