Thanks. As you said, the IDE is built on winforms, so it's windows only. maybe it was a mistake to not to use a cross platform framework like avalonia, but i really like the winforms designer, and winforms is the only UI framework i ever used, except for MAUI which is not a good idea to build an IDE on.
I really miss working with WinForms.
Every other UI framework I worked before and after always left me with the impression that something was lacking, in speed of development, fast iteration, but also in the quality of the abstractions.
Windows.Forms is becoming less of a problem with projects like LibreWinForms [0] progressing quickly. I just tried to build your project and there are only a few classes that are not implemented when it comes to the GUI.
[0] https://github.com/wieslawsoltes/LibreWinForms