When you select an entry in a list by clicking a checkbox, Joomla.isChecked is called, with the boolean this.checked as its first, and often only, parameter.
It uses that parameter to determine whether it should increase or decrease the count, stored in the hidden input boxchecked.
Instead of actually increasing or decreasing the value. It concatenates "1" or "-1" depending on whether you checked, or unchecked the box.
This fixes this, by using ++ and -- operators instead of += 1 and += -1
I have tested this item unsuccessfully on 03c0a70
issue already solved in an other way in 3.5.2
This comment was created with the J!Tracker Application at issues.joomla.org/joomla-cms/8495.