introduce a floem owned menu model for linux

[Third-Thing]

Goal: remove the Linux muda/GTK dependency, keep native menu support on macOS and Windows, and keep floem’s current public Menu API intact.

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Would anyone review/merge a pull request for this?

[luan-coelho]

I'd like to test this. I use Ubuntu and Manjaro on different machines.

[Third-Thing]

@luan-coelho Due to lack of maintainer availability/interest I have moved to working with gpui-component, which already has menus implemented for linux.

[Third-Thing]

@luan-coelho I did create working menus in app code.

That version is kept on https://github.com/Third-Thing/lazy-markdown/tree/floem-version/src/menus

You can appropriate that code as you wish.