ui: fix Button onclick handlers #294

Job	Run time
msvc (Debug)	4m 21s
ui	57s
formatting	1m 2s
msvc (Release)	4m 14s
linux (linux-amd64-release, linux-amd64)	1m 7s
linux (clang-tidy)	2m 13s
linux (linux-sanitizer)	1m 50s
macos (macos-x86_64, On)	7m 27s
linux (linux-debug, valgrind --suppressions=deps/osr/docs/tbb.supp --suppressions=deps/osr/docs/p...	4m 16s
openapi-validate	27s
macos (macos-arm64)	7m 50s
docker	24s
	36m 8s

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