When building any program that uses Gtkmm (with Atkmm support) ALL modules need to agree about the status of GTKMM_ATKMM_ENABLED. Otherwise 'Gtk::Widget' can have different sizes in different modules. If that happens we can end up with all manner of inexplicable run-time crashes and hangs.
GTKMM_ATKMM_ENABLED gets #defined in 'gtkmmconfig.h'. So let's #include that file at the earliest possible opportunity (where we know it'll then have a consistent value for every compilation unit).
John Emmas
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