Update tree tabs state properly (expand tabs, item counter)

[hluk]

No description provided.

[codecov]

Codecov Report

❌ Patch coverage is 53.57143% with 26 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.99%. Comparing base (2937f88) to head (227c2ab).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
src/gui/tabtree.cpp	16.00%	21 Missing ⚠️
src/gui/tabwidget.cpp	83.87%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3193      +/-   ##
==========================================
- Coverage   79.06%   78.99%   -0.08%     
==========================================
  Files         224      224              
  Lines       29861    29877      +16     
==========================================
- Hits        23611    23602       -9     
- Misses       6250     6275      +25     

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