Allow GPUI applications to run in the background

[Tryanks]

Recently, I have been using GPUI to write some applications. I want to develop a "service process with a settings interface," so naturally, I thought of keeping them running in the system tray.
To achieve this, I have read and learned about the following discussions in the community:

• linux: Implement tray icons #13098 implemented native tray-icon support for the Linux platform only (closed due to insufficient use cases)
• gpui: Allow the application to run after all windows are closed #36548 provides a way to keep the application running (still pending, and it does not address the need to expose the event loop)
• windows: Revert "Fix hide, activate method on Windows to hide/show application" #18571 The "hide" window method was called back because there was no way to restore the window (lacking features like a tray icon)
  For manually integrating external projects like tray-icon on the user side, there is no good way to keep the application running because releasing the GPUI instance also forcibly terminates the system process where the main thread is located. Moreover, there is also an issue of both sides competing for the main thread.

[jbirnick]

I have the same use case. I want to write some sort of daemon which constantly runs in the background, but can also spawn a "settings" window. To keep the app simple, this should use the same event loop / state.

In iced this is easy to do, but I don't know how to do it with GPUI. Any suggestions are welcome!

[Tryanks]

As you’ve seen, the current GPUI already provides a Quit mode that allows the process to keep running even after GPUI quits. So far, the only successful approach I’ve managed is integrating the tray-icon library, with some help from Claude.

Unfortunately, there isn’t any other convenient or official way to integrate a system tray icon with GPUI yet, and I don’t have a better suggestion at the moment — sorry :(

Also, since my own application is still under development, I’m unable to open-source it for now. Sorry again :(

Update:
Ah, I just noticed a new in-progress pull request for tray icon support — bless it. #44047