Hi guys I found a bug in the FFI installation of the etoys image. ByteArray>>#structAt:length: throws #externalCallFailed (the method has category nil, which I think is wrong also). I replaced it with a more recent version from the FFI package found in Universes and now is working:
ByteArray>>structAt: byteOffset length: length "Return a structure of the given length starting at the indicated byte offset." | value | value := ByteArray new: length. 1 to: length do:[:i| value unsignedByteAt: i put: (self unsignedByteAt: byteOffset+i-1)]. ^value
Cheers! Richo