as Robin said, he would like to look at gtk-osx, I just want to give some
infos about my last state for compiling CinePaint with this Gtk branch.
After the last talk on the CinePaint developers list I tried a Tiger
universal build with Gtk1 CinePaint v0.22-1. All deps where in place. Just
the CinePaint build did not run as expected on my G4 ppc test machine. For
intel I could not test.
Probably all is fine with building separately for ppc and intel.
I modified the G_ENDIAN style macros after configure, and exchanged
against runtime versions. In the same way I could change libtiff  to
open my test images properly. The other libs are probably not out of the
box osX universal binary ready.
Still the CinePaint build where not much useable. I could not draw.
The mouse position seems to be fixed. Even though the gradient,
selection and fill tools as well as colour selection and CMS worked.
Oh just fixed a Gtk1 bug in CinePaint CVS.
The outlined endianess gtk-osx changes are not included in my last patch