Esme Povirk (@madewokherd) commented about dlls/gdiplus/gdiplus_private.h:
GpBrush *brush; GpPenAlignment align; GpMatrix transform;
- REAL *compound_array;
- UINT compound_array_size;
This should probably match the type passed into `GdipSetPenCompoundArray`. Things can get weird in C when you compare between signed and unsigned types.