问题
Now that .net core support WinForms projects, I've ported an old project to .Net 5. I can edit code, desing GUI and compile, and everything seems to work fine except for Document Outline window (in Visual Studio 2019). All four buttons, move up, down, out and into, are disabled, so I cannot choose what to see on top at desing time.
I have created a new project from the scratch and those controls are still disabled.
Demo image:
Any idea why? I can guess it's something microsoft is working on, but I cannot find any reference to this issue.
That's how it looks like for .Net 4.5
来源：https://stackoverflow.com/questions/65901758/document-outline-controls-disabled-in-visual-studio-2019-for-net-core