With the introduction of the new event editor, Calendar saw it receive sections of editable properties of the events. One of these sections is the "Reminders" section, that contains the reminders (also called alarms) of an event. However, this section's row to add a new alarm does not match the proposed mockups for it. It currently has a combo box that shows the popover with selectable reminder times, instead of being a clickable row. Make it a clickable listbox row, and show the alarms popover when clicked. https://gitlab.gnome.org/GNOME/gnome-calendar/issues/502