desktop-apps | ONLYOFFICE Desktop Editors which builds the program | Editor library

How I came to the problem:
I setup an project like this: https://www.smashingmagazine.com/2020/07/desktop-apps-electron-vue-javascript/ until it came up to the coding part, there I added custom stuff. Created Components and so on. Everything works fine in serve then I want to build it.

What I expect as outcome:
App working as in serve mode

What I got:
blank page

What I've tried to fix the problem:
change a wide range of path urls like:

I try to build a GUI for given Python code using Electron. The data flow is actually straight-forward: The user interacts with the Electron app, which sends a request to the Python API, which processes the request and sends a reply.

So far, so good. I read different threads and blog posts:

1. ZeroRPC solutions:

• https://medium.com/@abulka/electron-python-4e8c807bfa5e
• https://github.com/fyears/electron-python-example

1. Spawn Python API as child process from node.js and communicate directly:

• https://www.ahmedbouchefra.com/connect-python-3-electron-nodejs-build-desktop-apps/
• This seems to be not the smartest solution for me, since using zeroRPC or zeroMQ makes it more easy to change the frontend architecture without touching the backend code.

1. Use zeroMQ sockets (for example exclusive pair?)

• https://zeromq.org/socket-api/#exclusive-pair-pattern

But in all three solutions, I struggle at the same point: I have to make asynchronous requests/replies, because the request processing can take some time and in this time, there can occur already further requests. For me, this looks like a very common pattern, but I found nothing on SO, maybe I just don't know, what exactly I am looking for.

I own the source code to a class library of "utilities" which I targeted to .NET Framework 4.8. I want to port it to use in a .NET Core desktop client app and port it to use in a .NET Core web service.

I know that new .NET Core projects have a new kind of project file that is described as SDK-style. It seems possible to verify VS is working with the new style because the first line of the project file mentions the word "sdk" and Visual Studio's right click on a project allows editing of the project file. The try-convert conversion tool is described as being incomplete and unsupported so I am pasting source code files into projects.

When I paste my source code into a Class Library (.NET Core) project it fails to compile for missing assemblies. There seems to be no way to add a reference to a Microsoft class like System.Windows.Documents.FlowDocument which is in PresentationFramework.dll. I can only add a COM Reference (not what I want) or Project Reference (in other words "home-made", not Microsoft, not what I want).

When I paste my source code into a WPF Library (.NET Core) project it compiles. This library has no WPF features because it is full of utility classes and utility methods so this project type seems a strange choice. I only guessed it might work because this tutorial mentions manually editing project files for WPF apps and Windows Forms apps. It does not tell you anything about any alternatives that are not apps. In other words, the tutorial does not mention libraries.

EDIT: The following question was edited to be "less broad" than the original.

Why does a WPF Library (.NET Core) succeed where Class Library (.NET Core) fails ?

Details: Visual Studio 2019 Community

RESOLUTION: "Class Library" worked when targeting .NET Framework 4.8 but now the choice must be "WPF Library" when targeting .NET Core. As @DavidAWhite says, FlowDocument is part of WPF.