Worth mentioning that workarea may not exist, and that we
return the full monitor geometry in that case.
* similar popups, to avoid placing them below panels, docks or other
* desktop components.
*
+ * Note that not all backends may have a concept of workarea. This
+ * function will return the monitor geometry if a workarea is not
+ * available, or does not apply.
+ *
* Monitor numbers start at 0. To obtain the number of monitors of
* @screen, use gdk_screen_get_n_monitors().
*