[bug] Qt WebEngine GPU/OpenGL failure causes fullscreen and rendering issues on Linux (requestFullscreen not working)

[vamshikrishna781]

Summary

Hi,

I am using the Linux version of Safe Exam Browser (jvr2022/seb-linux), and I am facing issues related to GPU/OpenGL rendering which affect fullscreen functionality and overall stability.

Issue Summary

• SEB fails to initialize OpenGL/Vulkan context
• Browser rendering falls back or breaks
• requestFullscreen() does not work (throws error: "Fullscreen is not supported")
• This affects exam environments where fullscreen enforcement is required

Error Logs

QCommandLineParser: option not defined: "dev-bypass"
This plugin does not support createPlatformOpenGLContext!
QRhiGles2: Failed to create context
QVulkanInstance: Failed to initialize Vulkan
Unable to detect GPU vendor.
js: Uncaught (in promise) TypeError: Fullscreen is not supported

Steps to Reproduce

1. Run SEB with a local .seb config or URL:
   safe-exam-browser file:///path/to/test.seb
2. Load a page that uses:
   document.documentElement.requestFullscreen()
3. Observe failure in fullscreen and console errors

Expected Behavior

• SEB should support fullscreen via requestFullscreen()
• Proper fallback to software rendering if GPU is unavailable

Actual Behavior

• Fullscreen API fails
• Rendering backend errors (OpenGL/Vulkan)
• SEB UI partially works but lacks full functionality

Environment

• OS: Linux (Kali / Ubuntu-based)
• SEB Version: (mention your version)
• Installation: GitHub repo (jvr2022/seb-linux)

Workarounds Tried

• QTWEBENGINE_CHROMIUM_FLAGS="--disable-gpu"
• QT_QUICK_BACKEND=software
• LIBGL_ALWAYS_SOFTWARE=1

These reduce errors but do not fully fix fullscreen support.

Suggestion

• Provide a stable software-rendering fallback
• Ensure fullscreen API works even without GPU acceleration
• Improve error handling/logging for graphics backend

---

This issue impacts the ability to simulate real exam environments on Linux.

Thanks!

Steps to reproduce

1. Start a local server:
   python3 -m http.server 8000

2. Launch Safe Exam Browser with a local .seb file or URL:
   safe-exam-browser file:///var/www/html/sebtest/test.seb
   OR
   safe-exam-browser http://127.0.0.1:8000/seb-test1.html

3. Open a page that uses fullscreen API:
   document.documentElement.requestFullscreen()

4. Observe that fullscreen does not activate and console shows errors.

Expected behavior

• Fullscreen should work using requestFullscreen()
• SEB should properly initialize rendering backend (OpenGL/Vulkan)
• If GPU is unavailable, SEB should fallback to software rendering
• Exam UI should run in fullscreen mode without errors

Actual behavior

• Fullscreen API fails with error: "Fullscreen is not supported"
• OpenGL/Vulkan initialization fails
• Rendering backend errors appear in logs
• SEB loads page but does not support fullscreen or proper rendering

Version

0.5.1

Linux distribution

Ubuntu

[Jvr2022]

I will take a look into this! Thanks for reporting!