Comment 9 for bug 1085972

I got this error as I wrote a plugin for firefox. I used the basic plugin outline from: <http://stackoverflow.com/questions/8507670/basic-plugin-npapi-npruntime-hello-world>.

When I want to initialize Gtk3 (gtkmm) in the NP_Initialize function with:

Gtk::Main::init_gtkmm_internals ();

then it hangs and I got the following (same) errors:

(plugin-container:21564): GLib-GObject-WARNING **: cannot register existing type `GdkWindow'
(plugin-container:21564): GLib-CRITICAL **: g_once_init_leave: assertion `result != 0' failed

I guess the error commes from because firefox uses Gtk2 and when a plugin used Gtk3 then there are so strange errors.