Fixes abst and abst-end values for frames element #294

Job	Run time
build-linux (gcc-9)	5m 12s
build-linux-Qt6 (gcc-9)	6m 24s
build-macos-brew (clang-9)	4m 34s
build-macos-brew-Qt6 (clang-9)	3m 46s
build-macos-no-brew (clang-9)	6m 30s
build-windows-mingw (5.15.*)	15m 1s
build-macos-no-brew-Qt6 (clang-9)	5m 51s
build-windows-mingw-Qt6 (6.5.*, qtmultimedia qt5compat)	17m 34s
build-windows-vs (5.15.*)	11m 46s
build-windows-vs-Qt6 (6.3.*, qtmultimedia qt5compat)	17m 47s
	1h 34m 25s

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