[Bug]: Changing z-pos doesn't work for some particles and objects

[Eauix]

SuperTux Version

v0.6.3-1277-g72553fe82

System Information

Windows 10, 64-bit

Expected Behavior

The objects appear in front of a tilemap with z-pos lower than the z-pos you set into the object.

Actual Behavior

The objects appear only in front of a tilemap with z-pos lower than 0, or -99 in case of the door

Steps To Reproduce Actual Behavior

Place a door, a conveyor, a rain particle or a custom particle and try to change its z-pos to appear behind or in front of a tilemap, it won't do anything.

Additional Information

• Every object and particle shown in this image have their z-positions set to 999, they should appear in front of all 4 tilemaps, yet, they appear behind some of them.

• Doors seem to be stuck at z-pos -99 regardless of you changing it or not. Rain particles, Custom particles and Conveyors seem to be stuck at z-pos 0 regardless of you changing it or not.

• Rain and particles only change their z-pos visually in editor, but not when playing the level.

• Custom particles don't change their z-pos.

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• All objects except for these ones seem to work properly when changing their z-positions.

• Cloud and Snow particles work properly when changing their z-pos

Guidelines For Reporting Issues

• [X] I have read https://github.com/SuperTux/supertux/blob/master/CONTRIBUTING.md#bug-reports.
• [X] I have verified this isn't an issue that's already been reported.
• [X] 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.
• [X] I have verified this issue is not about wrong translations (use Transifex for those), or anything unsupported (e.g. third-party add-ons).
• [X] In this report, I have only included details about one (1) bug.
• [X] 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.

[tobbi]

I looked and those objects have their z-position / layer hardcoded to some value. Someone'd have to change that in order for the setting to work.

[provigz]

Should be fixed by commit c12c2bb8aa12fd01ce8c83da59ab0cf252ab59b0. Please test!