[Bug]: Rooted Forest: corrupted worldmap theme does not persist

[STEMathematics]

SuperTux Version

supertux2 dev v0.7.0-beta.2 - 3f3d0e1 (master)

System Information

Linux Mint 22.3 - Cinnamon 64-bit

Expected Behavior

After exiting a level or cutscene in the corrupted forest, the worldmap theme is the corrupted forest one.

Actual Behavior

After exiting a level or cutscene in the corrupted forest, the worldmap theme is the normal forest one.

2026-02-13.17-02-32.mp4

Steps To Reproduce Actual Behavior

1. Go to the Rooted Forest (story mode).
2. Go to the uncorrupted section.
3. Go to the corrupted section.
4. Enter a level or cutscene.
5. Leave the level or cutscene.

Additional Information

No response

Guidelines For Reporting Issues

• I have read https://github.com/SuperTux/supertux/blob/master/CONTRIBUTING.md#bug-reports.
• I have verified this isn't an issue that's already been reported.
• I have verified this isn't a discussion, or an issue about a crash or a feature request, but rather an actual bug ─ that is, the game did something not intended.
• I have verified this issue is not about wrong translations (use Transifex for those), or anything unsupported (e.g. third-party add-ons).
• In this report, I have only included details about one (1) bug.
• If I make a mistake while submitting this report, I agree to use the "Edit" feature to correct it, instead of closing this issue and opening a new one.