The attachment adds the handling of (already globally existing) USE flags "examples" and "demos". The default is off for both. If on, respective parts are built and installed additionally, which is interesting for developers using this fine library.
Created attachment 94004 [details, diff] adds and handles examples and demos USE flags
Created attachment 94005 [details, diff] same patch with default flag setting off replaces previous
sounds good better to set G2CONF in pkg_setup though, keep the eclass functionality in tact as much as possible.
Created attachment 94879 [details, diff] same patch leaving G2CONF in ah I see now what you mean. to make use flags turned off per default, simply saying IUSE='-flag' won't work. instead, one defines them in IUSE, and disables via G2CONF.
(of course the header should not be patched) Finally, if you agree, then I'll attach a snippet patching all current ebuilds in dev-cpp/gtkmm
examples is added in 2.10 series, if you enable examples you should get demos as well. in cvs.