The Desktop App Converter (or Project Centennial) is a way of packaging up traditional desktop applications in appx format for the Windows 10 store. You would commonly use it for modernising an existing app. This allows you to take advantage of store distribution and incrementally add modern functionality to it.
My requirement was a little different. I needed a way of adding functionality to a UWP app which is not currently possible via UWP. The functionality in question was the ability to show a progress bar on the desktop taskbar entry. If you don’t know what I mean by this it is what you get with many desktop installers or other apps which make large downloads to keep you informed of progress while you do something else. There are two ways of approaching this – you can include a desktop “full-trust” component inside the same app package as a UWP app allowing you to mix and match and submit to the store as a single entity but this requires the developer to get full trust certification each time you repeat the process. The other approach is to build a standalone desktop bridge app to call the Win32 APIs necessary to control the taskbar and have other UWP apps call into this via an API. This way once the enabling app has gone through certification subsequent UWP apps can make use of it without any special permissions. Underneath there is a simple Uri scheme to request taskbar changes and so the caller won’t throw an error if the “Taskbar Progress” app isn’t installed.
The API to call this is already part of Pontoon as the. This mirrors the API in UWP which is only available on phone devices. We wrap the functionality for you so there is a common API across mobile and desktop flavours of Windows as well as Android and iOS (although iOS is limited to a indeterminate spinner).
I have a very basic sample app which I’m just waiting to convert from private to public in the store and will update this post with a link when published.