sandbox: Condensed `renderUI` + fellow subsections #397

Job	Run time
Build (ubuntu-latest, mkdir build cd build cmake -DCPACK_GENERATOR=DEB .. cmake --build . cpack -...	3m 23s
Build (windows-latest, mkdir build cd build cmake -DCPACK_GENERATOR=ZIP -G "NMake Makefiles" .. c...	5m 10s
Build (macos-latest, mkdir build cd build cmake -DCPACK_GENERATOR=ZIP .. cmake --build . cpack -C...	4m 39s
Release	0s
	13m 12s

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