Sorry we didn't get to see this on 31 December 2017 - it seems like its either an end of month or end of year issue. Have you noticed it before at the end of a month?

I didn't notice this at the end of a month, only at the end of the year. Some days ago I remember (80 per cent sure) having seen two "current" days again: Dec. 1st and the real current day.

If you change the code in modules/mod_jevents_cal/tmpl/ext/calendar.php at lines 211-215 from

						$class = ($currentDay["cellDate"] == $today) ? "extcal_todaycell" : "extcal_daycell";

						$linkclass = "extcal_daylink";

						if($dayOfWeek==0 && $currentDay["cellDate"] != $today) {

							$class = "extcal_sundaycell";

							$linkclass = "extcal_sundaylink";

						}

to

						$class = $currentDay["today"] ? "extcal_todaycell" : "extcal_daycell";

						$linkclass = "extcal_daylink";

						if($dayOfWeek==0 && !$currentDay["today"]) {

							$class = "extcal_sundaycell";

							$linkclass = "extcal_sundaylink";

						}

it should resolve this issue

Will you include this patch into your next update of jevents?

yes - the change will be in the next release of JEvents