PDFKit and 64-bit bugs

I've finally moved to upgrade a PDFKit app to 64-bits. However, it's  
giving me all kinds of crashers which I'm pretty sure are bugs in  
PDFKit. It seems that whenever I call -[PDFBorder dashPattern] or - 
[PDFPage attributedString] it crashes, and on 10.5.8 also -[PDFView  
areaOfInterestForMouse:] (though that seems to originate in -[PDFPage  
loadTextChars]). I've found some ugly workarounds for the first two,  
but the last one remains illusive.

I wonder whether others on this list had similar problems? And in  
particular, whether others know workarounds for these bugs, in  
particular the third one?

Thanks,
Christiaan