To help you out with OSX testing, I tried out your gem installation.
Sadly it did not work Here is the build log:
Fetching: pkg-config-1.1.3.gem (100%)
Fetching: glib2-1.1.2.gem (100%)
Building native extensions. This could take a while…
Fetching: atk-1.1.2.gem (100%)
Building native extensions. This could take a while…
ERROR: Error installing gswax:
ERROR: Failed to build gem native extension.
checking for atk... no
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers. Check the mkmf.log file for more
details. You may need configuration options.
Seems one needs to install GTK+ on OSX before installing your gem,
through something like brew or MacPorts. I have no actual need for your
program now and have no other programs that needs GTK+, so I’m afraid I
cannot help you with testing this out.
Also looked at your installation docs for Windows. Is this what you need
for getting the gem to work there:
Where is your gemspec located? Did not see it on GitHub.