UiSystem::Layout is run too late in the schedule about bevy

[eidloi]

This issue can be reproduced in sickle_ui:

Checkout https://github.com/UmbraLuminosa/sickle_ui/tree/55405d0c4bc39be0a7937d936eb9235b11916a7b
uncomment line https://github.com/UmbraLuminosa/sickle_ui/blob/55405d0c4bc39be0a7937d936eb9235b11916a7b/crates/sickle_ui_scaffold/src/theme/pseudo_state.rs#L22 (and import the enum)

Start the example cargo run --example simple_editor

If the line is commented out it will start normally.

NOTE: The branch points to local bevy folder instead of the repo!

[benfrankel]

Adding a system that is both .after(VisibilityPropagate) and .before(ThemeUpdate) implicitly forces VisibilityPropagate to run .before(ThemeUpdate), which in turn runs .before(UiSystem::Layout).

This creates a cycle:

1. TransformPropagate
2. VisibilityPropagate
3. propagate_visibility_to_pseudo_state
4. ThemeUpdate
5. UiSystem::Layout, which contains ui_layout_system
6. TransformPropagate

[eidloi]

Adding a system that is both .after(VisibilityPropagate) and .before(ThemeUpdate) implicitly forces VisibilityPropagate to run .before(ThemeUpdate), which in turn runs .before(UiSystem::Layout).

This creates a cycle:

1. `TransformPropagate`

2. `VisibilityPropagate`

3. `propagate_visibility_to_pseudo_state`

4. `ThemeUpdate`

5. `UiSystem::Layout`, which contains `ui_layout_system`

6. `TransformPropagate`

Yes, and looking at VisibilityPropagate it is set only after TransformPropagate. Does this mean TransformPropagate moved later in the schedule in 0.14 or was UiSystem::Layout moved earlier? I didn't have this issue before.

[eidloi]

BTW this is not blocking for the moment, It just means that the theme in sickle_ui will be updated a frame later in some cases, but I have to see how much noticeable flicker it introduced.