param([string]$LogPath = "$env:TEMP\waiting-log.txt")
function Write-Log($m){ try{"[$(Get-Date -Format o)] $m" | Out-File $LogPath -Append -Encoding UTF8}catch{} }

try{
  [System.Threading.Thread]::CurrentThread.TrySetApartmentState('STA') | Out-Null
  Add-Type -AssemblyName PresentationFramework | Out-Null

  $xaml = @'
<Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        Title="Installing..." Width="420" Height="160"
        WindowStartupLocation="CenterScreen" ResizeMode="NoResize" Topmost="True">
  <Grid Margin="16">
    <StackPanel>
      <TextBlock Text="Installing the new version, please wait..." Margin="0,0,0,12" FontSize="16" FontWeight="Bold"/>
      <ProgressBar IsIndeterminate="True" Height="18"/>
      <TextBlock Name="Status" Margin="0,10,0,0" Opacity="0.8" Text="Do not close your computer."/>
    </StackPanel>
  </Grid>
</Window>
'@

  $win = [Windows.Markup.XamlReader]::Parse($xaml)
  Write-Log "ShowDialog begin"
  $null = $win.ShowDialog()
  Write-Log "ShowDialog end"
}catch{
  Write-Log "FATAL: $($_.Exception.Message)`n$($_.Exception.StackTrace)"
}