Why does 0.99.xx get GTK errors when compiling?
If you are seeing complaints about the wrong number of arguments for some gtk function[s], and/or an unresolved reference to some gtk function[s], you need a newer version of GTK. Get it at ftp://ftp.gimp.org/pub/gtk/ . After you build it, remove any old versions (or move them elsewhere) and install the new version. The GIMP build process insists on using the installed gtk+ libraries at this time.