embedding external windows doesn't work

Is your issue REALLY a bug?

[x] My issue is indeed a bug!
[x] I am not crazy! I will not fill out this form just to ask a question or request a feature. Pinky promise.

Is there an existing issue for this?

[x] I have searched the existing issues.

Is this issue related to iced?

[x] My hardware is compatible and my graphics drivers are up-to-date.

What happened?

Embedding an external window via the run_with_handle function doesn't work correctly.

I assume this is because the runtime doesn't know not to draw into the window, so there would need to be a way to spawn a window that is ignored while drawing / widgeting. I don't think anything else would be necessary for this to work, since it's already fairly easy to intercept window events via subscriptions, however a way to disable wayland (it doesn't support embedding) would be nice IMO.

This was already discussed on discord a few weeks back, just opening this issue to track progress etc

iced-rs / iced