Keeping GNUstep apps from linking in Apple libs

Hi,

 Still trying to build my app that consists of one application, one 
framework and one loadable bundle. The app and the bundle both link with 
the framework.

 I've added the framework to the makefile using

   ADDITIONAL_NATIVE_LIBS += PreferencePanes

and I also tried

   ADDITIONAL_GUI_LIBS += -lPreferencePanes

everything compiles just fine, but when I call openapp, I get loads of 
error messages complaining about duplicate symbols. They're usually like:

objc: Both 
/usr/GNUstep/System/Library/Libraries/libgnustep-base.dylib.1.10
and
/System/Library/Frameworks/Foundation.framework/Versions/C/Foundation
have implementations of class
NSCalendarDate
objc: Using implementation from
/System/Library/Frameworks/Foundation.framework/Versions/C/Foundation

Now, this obviously leads to a bus error, because sometimes it picks 
stuff from Apple, and sometimes from GNUstep.

What can I do to "hide" the stuff in /usr/lib and 
/System/Library/Frameworks from my compiler?

Thanks for your help,
-- M. Uli Kusterer
http://www.zathras.de