https://gitlab.gnome.org/GNOME/gtk/merge_requests/1371#note_699272
gdk_monitor_get_refresh_rate
GdkSubpixelLayout
gdk_monitor_get_subpixel_layout
-gdk_monitor_is_primary
gdk_monitor_is_valid
<SUBSECTION Standard>
* such as panels should place themselves on the primary monitor.
*
* If no monitor is the designated primary monitor, any monitor
- * (usually the first) may be returned. To make sure there is a dedicated
- * primary monitor, use gdk_monitor_is_primary() on the returned monitor.
+ * (usually the first) may be returned.
*
* Returns: (transfer none): the primary monitor, or any monitor if no
* primary monitor is configured by the user