Here's what I did in glade. Made 2 GtkRadioMenuItem, and for the group, set them to each other, so only one can be on at a time. Then attached a "on_horizontal_bar_toggled" handler to the "toggle" signal of one. I used the gtkbuilder to connect the signals, and I do this in my callback function:
void on_horizontal_bar_toggled(GtkCheckMenuItem * button, VadiGui * gui)
Now, when the program starts, I get this: "Gtk-CRITICAL **: gtk_radio_action_set_group: assertion `!g_slist_find (group, action)' failed". I suspect I was only supposed to add one radio button to the other, not both ways like I did - however Glade isn't allowing me to erase the field now. But only 1 button is checked at a time, so it's sort of ok.
Sort of because button->active always returns 0, even if the button is on. Any ideas on whats going wrong? I'm lost.