Accessibility of GTKMenuButtons not ideal
When reviewing the accessibility of gnome-text-editor, i came across many GtkMenuButtons. All of them had only tooltips. Because of the current implementation, the visually impaired user only gets the somewhat unhelpful message that he landed on a GtkToggleButton (because of the focus event handler) and there is no way how to set the accessibility label for this button from outside. I am not experienced with GTK enough, so i was not able to find a way how to react on tooltip changes of the widget and update the label accordingly, so if there are any tips, i am more than happy to make a MR. Yes, it would likely be also necessary to update the accessibility label during an update of the visible label, because the button gets it in a non-standard way (at least for the button it is not the same as a button_set_label call), but that would not solve the current issue in gnome-text-editor.