Toggling the system property glide.ui.list_edit.show_calendar_only between true and false appears to alter no behaviour.
Is a true/false system property and changes to this property are only shown on the list view, not the form as some users are expecting. The behaviour is shown below.
Appearance in list view when value is set to True (default)
Appearance in list view when value is set to False
The additional widget allows direct modification of the date/time in the list view. When opening via the form direct modification can be done directly on the field so the additional popup is not required.
PRB1241416 - System property glide.ui.list_edit.show_calendar_only is ignored