Pushing a screen at OnExiting without blocking the exit freezes the UI

[mcendu]

Per title. The following test if put in TestSceneScreenStack triggers it. I am not sure what is the intended behavior here.

        [Test]
        public void TestPushOnExitingWithoutBlocking()
        {
            TestScreen screen1 = null;

            pushAndEnsureCurrent(() =>
            {
                screen1 = new TestScreen(id: 1);
                screen1.Exiting = () =>
                {
                    screen1.Push(new TestScreen(id: 2));
                    return false;
                };
                return screen1;
            });

            AddStep("Exit screen 1", () => screen1.Exit());
        }

[peppy]

It's undefined behaviour (you're pushing a new screen to a screen that you've implied to be exited).

So let me ask you then: what do you expect in this scenario? what are you trying to make happen here? the new screen pushed to the parent in the stack?

[peppy]

This shouldn't be closed (it does need a resolution, even if that is just throwing an exception). Could you answer my question to help us decide how this behaves or offer an alternative?

[mcendu]

I think it is good to throw an exception here (maybe ScreenNotCurrentException); nobody is going to expect such a thing to happen IMO.