chore: Fix dummy app fixed elements rendering

[tvdeyen]

We need to use the render_elements helper in order to render fixed elements. Otherwise the public version will be used. This leads to the click-element-to-focus feature not working.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.48%. Comparing base (06e0f92) to head (80f5157).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3614   +/-   ##
=======================================
  Coverage   97.48%   97.48%           
=======================================
  Files         314      314           
  Lines        8256     8256           
=======================================
  Hits         8048     8048           
  Misses        208      208           

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