GitHub: fix #464 Reported by cedlemo. Thanks!!!
GDK's thread documentation says: > GTK+, however, is not thread safe. You should only use GTK+ and GDK > from the thread gtk_init() and gtk_main() were called on. This is > usually referred to as the "main thread". https://developer.gnome.org/gdk3/stable/gdk3-Threads.html#gdk3-Threads.description