https://developer.gnome.org/gdk2/stable/gdk2-Keyboard-Handling.html#gdk-keym...
Note that passing `NULL` for `keymap` is deprecated and will stop to work in GTK+ 3.0. Use [`gdk_keymap_get_for_display()`](https://developer.gnome.org/gdk2/stable/gdk2-Keyboard-Handling.html#gdk-keym...) instead.