I edited AboutSystem.cpp and built it as MyAboutSystem.
Then, it surprisingly worked well. (Of course, I used rc and xres to apply AboutSystem.rdef.)
When I type MyAboutSystem while it’s already working, it focuses on the running window. (and it doesn’t create a new window.)
When I type MyAboutSystem -v after that, it displays the version info.
Presumably app.Run() focuses on the running window and terminates its own process.
The code before app.Run() runs correctly.
Idk if I’ve verified this correctly tho. I haven’t rebuilt the whole system, and there is so much about Haiku that I don’t know.