With a python framework with DEPLOYMENT_TARGET 10.5, if I build pyobjc on a 10.8 machine and then deploy an application to a 10.5 machine the application fails to load properly because Quartz.CoreGraphics._coregraphics cannot be loaded due to a link error for CGBitmapContextCreateWithData.
That symbol is available starting OSX 10.8, and hence not on 10.5. However, the symbol should have been weak-linked but isn't.
Current workaround: just patch _coregraphics to exclude the symbol. That is suboptimal and a better fix needs to be found.