Palette elements (Class, Enumeration) shake while scrolling the surrounding container

[az108]

Describe the bug

In the Apollon editor, the palette element options (e.g. Class and Enumeration) visibly shake / jitter while the surrounding page/container is scrolled. The palette items wobble as the view scrolls, which looks glitchy.

This was found in Artemis (which embeds @tumaet/apollon 5.0.1) while a modeling exercise was scrolled. It reproduces on the current Artemis develop, and is independent of any Artemis drag-and-drop code (Artemis does not wrap the palette in its own drag handling) — it appears to be an Apollon repaint-on-scroll behavior.

To Reproduce

Steps to reproduce the behavior:

1. Open the Apollon editor inside a scrollable container (e.g. a modeling exercise in Artemis, where the exercise view scrolls).
2. Scroll the container up/down while the Apollon editor and its palette are visible.
3. Observe the palette element options (e.g. Class, Enumeration) shaking/jittering during the scroll.

Expected behavior

The Apollon palette elements should stay stable and render smoothly while the surrounding view is scrolled.

Screenshots / recording

Screen recording (jitter visible around timestamp 00:18):

Screen.Recording.2026-07-12.at.13.15.05.mov

Version

• Apollon (@tumaet/apollon): 5.0.1
• Observed via Artemis (reproduces on Artemis develop)

Additional context

Originally reported in Artemis: ls1intum/Artemis#13205 (moved here as it belongs to the Apollon editor). Spotted during Artemis PR ls1intum/Artemis#13190.