Roman

Definitely make it WPF

Or maybe even better directly Cross-Plattform (Avalonia UI?) as FlaUI will be ported to .Net Core/Standard soon and maybe will support gtk and Avalonia and such.

No, the GUI app stays open. I also manually created a shim with the GUI flag to make really sure it is correctly flagged.

The shim exe is a command line app I suspect. Would it be possible to have a shim exe with an invisible gui for that case?

There's many possibilities to achieve this. I think WinForms is easier and has a much smaller footprint than WPF. Here's a google result as a start: - http://stackoverflow.com/questions/683896/any-way-to-create-a-hidden-main-window-in-c

This might also be worth a try: > Create a new console app then then change the "Output Type" type to "Windows Application" (done in the project properties) (Source: http://stackoverflow.com/questions/836427/how-to-run-a-c-sharp-console-application-with-the-console-hidden)

Unfortunately, the binaries are not ARM compatible and I could not find any project that started working on that.

The newest OldUnreal469d patch actually includes arm binaries, open for a PR to include this.

That is strange, it should work out of the box (just tested it). Where are you running it? Can you post the entire log from the docker container?

Is it 32 or a 64 bit system?