Something I forgot to mention: the patch introduces "_tkinter.m" to enable compiling the _tkinter extension as Objective-C code.  The compiler also supports passing "-x objective-c" to compile _tkinter.c in Objective-C mode, but this flag must be specified early on the GCC command-line and I haven't been able to trick distutils in passing the flags at the right place yet.

Just adding ['-x', 'objective-c'] to the extra_compile_args argument to Extension does not work: that appends the flags to the compiler command-line while the -x flag only works when it is before the name of the source file(s).