All events in month-popover displays hour-label indicating their start time, but all-day events should not display their start time. This is caused by gtk_widget_show_all recursively setting the events list-box and all its childrens visible. We replace gtk_widget_show_all with gtk_widget_show to show the events list-box and its childrens. https://gitlab.gnome.org/GNOME/gnome-calendar/issues/250