No, you can’t indeed, because the yarn editor is part of GDevelop. Just like Piskel, JFXR, and about any open window, you can’t use the GDevelop editor until you close the secondary window.
If bugs are found, they’ll be fixed, but I wouldn’t expect much in terms of updates.
Well, I see from your screenshots that the position is saved indeed, only one node is not at the right position…Why, I don’t know, maybe it’s the last one you added?
If you open your dialogue file in a text editor, you’ll see that the position and colour are saved:
Regarding the minimize/maximize/close buttons, these are standard Windows buttons, there is no meaning behind it.
Currently the problem occurs with two nodes but they aren’t the last ones added. I will post more pictures to help understand the source of the problem.