[benoit-pierre]

▸ rm -rf build && cmake -S lib -B build -G Ninja -DBUILD_SHARED_LIBS=ON -DCMAKE_BUILD_TYPE=Debug
▸ ninja -C build
▸ gdb --batch -ex 'set trace-commands' -ex 'print sizeof (WILLUSBITMAP)' -ex 'print sizeof (KOPTContext)' build/libk2pdfopt.so

# Before:
+symbol-file build/libk2pdfopt.so
+print sizeof (WILLUSBITMAP)
$1 = 3104
+print sizeof (KOPTContext)
$2 = 6456

# After:
+symbol-file build/libk2pdfopt.so
+print sizeof (WILLUSBITMAP)
$1 = 800 # ÷3.9
+print sizeof (KOPTContext)
$2 = 1848 # ÷3.5

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This change is 

[benoit-pierre]

Added 7971711 for posterity.