Bean cannot load NIB file

[Fred Kiefer]

Due to some of my recent changes the Bean application in gap is no 
longer starting correctly. What happens is rather interesting. I added 
binding support for the NSColorWell and Bean has been using this 
feature, but it wasn't supported in GNUstep. Now that it is, a problem 
on a deeper level got revealed. Bean has a defaults.plist file that 
stores some user default settings for the application. This includes the 
default colours for altBackgroundColor and altTextColor. These colours 
are stored as NSData containing the archived colours.

        <key>altBackgroundColor</key>
        <data>
        BAt0eXBlZHN0cmVhbYED6IQBQISEhAdOU0NvbG9yAISECE5TT2JqZWN0AIWEAWMBhARm
        ZmZmgzyXxIiDPlaH04M+mOesAYY=
        </data>
        <key>altTextColor</key>
        <data>
        BAt0eXBlZHN0cmVhbYED6IQBQISEhAdOU0NvbG9yAISECE5TT2JqZWN0AIWEAWMBhARm
        ZmZmAQEBAYY=
        </data>

gdb reports the later value as:
(gdb) po anObject
<040b7479 70656473 74726561 6d8103e8 84014084 8484074e 53436f6c 6f720084 
84084e53 4f626a65 63740085 84016301 84046666 66660101 010186>

Starting from byte three this reads "typedstream". Now this is Apple 
format used for NSArchiver and GNUstep isn't able to read this.

The simplest solution is of course just to delete this entries from the 
defaults.plist. On the other hand I remember somebody telling me that he 
wrote a reader for this archive format. Going down that road would mean 
to replace all our non-keyed archive implementations.

Any ideas on how to handle this best?