UI widgets drawn in wrong place after toggling fullscreen → windowed (click targets remain at old positions)

### Intro

Hi!

I’m a BCA graduate from Maharaja Surajmal Institute. I discovered MuJoCo while exploring machine learning and open-source, and it really caught my interest, which led me to start learning more about it.

### My setup

1 was using MuJoCo v3.4.1 on Ubuntu 24.04.3 LTS, and I performed debugging using Visual Studio Code.

### What's happening? What did you expect?

After switching the MuJoCo window from fullscreen back to windowed, the UI widgets (buttons, panels) are visually shifted (e.g. the Fullscreen button draws higher), but their clickable areas remain at the previous positions. Clicking the visible widget does nothing; clicking where it was before (now empty) triggers the action.

Video : -

https://github.com/user-attachments/assets/fda1cedd-02bb-4d2d-bec1-9afcf6d8582a

### Steps for reproduction

1. Open mujoco (no special model required).
2. From the UI, toggle Fullscreen (Option → Fullscreen or the fullscreen button).
3. Toggle Fullscreen again to return to windowed.
4. Observe that some UI elements are visually misplaced while clicks still register at the old coordinates.

### Minimal model for reproduction

_No response_

### Code required for reproduction

_No response_

### Confirmations

- [x] I searched the [latest documentation](https://mujoco.readthedocs.io/en/latest/overview.html) thoroughly before posting.
- [x] I searched previous [Issues](https://github.com/google-deepmind/mujoco/issues) and [Discussions](https://github.com/google-deepmind/mujoco/discussions), I am certain this has not been raised before.