easytag | git repo of the development series

In certain applications from GNOME, like EasyTAG, in their source code they have constructs like G_DEFINE_TYPE, and et_application_get_type (from EasyTAG). They use GAction varibles to represent actions that are run from the menubar, eg. for the Quit item, they would represent it in the GAction array of possible actions. In other applications, like LXTask, GManEdit, they use signal handlers to call the function that processes the request (to quit, maybe).

Which should I use: The first or second.

I have noticed that if you use the first way, the source files are divided into files named window, application_window, preferences_window, eg. The second method uses the prenamed callbacks.c, interface.c always.
When browsing source code, I find the second method easier to read, because if I want to look for some functionality, i know which file to look in. The first method is not so easy because it is named after window elements, not preset filenames.

Maybe the first method is more efficient for the compiler...Any idea?