WPF - Download Manager With Async Task

Here, 1 NuGet package is used for showing watermark-

https://www.nuget.org/packages/Gu.Wpf.Adorners/

if you are getting error using that, please run this command in NuGet command prompt-

Get-Package

Even if not working, then please try this-

Install-Package Gu.Wpf.Adorners
Uninstall-Package Gu.Wpf.Adorners
Install-Package Gu.Wpf.Adorners

Thanks