fix: gui-extended-example

[germa89]

Description

Fix and improve the GUI example.

Issue linked

Close #3537

Checklist

• I have visited and read Develop PyMAPDL.
• I have tested my changes locally
• I have added necessary documentation or updated existing documentation.
• I have followed the PyMAPDL coding style guidelines.
• I have added appropriate unit tests that also ensure the minimal coverage criteria.
• I have reviewed my changes before submitting this pull request.
• I have linked the issue or issues that are solved to the PR if any.
• I have assigned this PR to myself.
• I have marked this PR as draft if it is not ready to be reviewed yet.
• I have made sure that the title of my PR follows Commit naming conventions (e.g. feat: adding new MAPDL command)

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.27%. Comparing base (abcb5ae) to head (0d2b490).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3555      +/-   ##
==========================================
- Coverage   91.28%   91.27%   -0.02%     
==========================================
  Files         187      187              
  Lines       14638    14638              
==========================================
- Hits        13363    13361       -2     
- Misses       1275     1277       +2     

---- 🚨 Try these New Features:

• Flaky Tests Detection - Detect and resolve failed and flaky tests

[germa89]

Also close #3531

[germa89]

@ansjhajjar, can you review this PR?

[ansjhajjar]

LGTM