More minor ImGui fixes #10277

Job	Run time
build-windows (x64)	10m 0s
build-windows (ARM64)	10m 19s
build-uwp	9m 15s
build_test_headless_alpine	13m 27s
build (ubuntu-latest, test, clang, clang++, ./b.sh --headless --unittest, clang-normal)	3m 42s
build (ubuntu-latest, gcc, g++, ./b.sh --headless --unittest, gcc-normal)	3m 11s
build (ubuntu-latest, android, clang, clang++, cd android && ./ab.sh -j2 APP_ABI=arm64-v8a UNITTE...	9m 55s
build (ubuntu-latest, android, clang, clang++, cd android && ./ab.sh -j2 APP_ABI=armeabi-v7a UNIT...	7m 9s
build (ubuntu-latest, android, clang, clang++, cd android && ./ab.sh -j2 APP_ABI=x86_64 UNITTEST=...	10m 48s
build (ubuntu-latest, android, clang, clang++, cd android && ./ab.sh -j2 APP_ABI=arm64-v8a OPENXR...	9m 39s
build (ubuntu-latest, android, clang, clang++, ./b.sh --libretro_android ppsspp_libretro, android...	5m 3s
build (ubuntu-latest, qt, gcc, g++, ./b.sh --qt, qt)	4m 11s
build (ubuntu-latest, libretro, gcc, g++, make -C libretro -f Makefile -j2, gcc-libretro)	2m 46s
build (ubuntu-latest, libretro, clang, clang++, make -C libretro -f Makefile -j2, clang-libretro)	2m 59s
build (macos-latest, test, clang, clang++, ./b.sh --headless --unittest --fat --no-png --no-sdl2,...	10m 23s
build (macos-latest, ios, clang, clang++, ./b.sh --ios, ios)	4m 23s
test-windows	1m 10s
test (ubuntu-latest)	1m 15s
test (macos-latest)	1m 29s
	2h 1m 4s

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