onclick event doesn't fire when targets of mousedown and mouseup events differ (but both are inside of element with onclick handler)
You can check this issue here: https://jsfiddle.net/wt98ukw7/3/ onclick event fires only on upper half of div2, because in this case target of mousedown and mouseup events is div2. But if you click on bottom half of div2, target of mousedown event is div2 and target of mouseup is div1. I think it's a bug and it should be fixed.
Alle antwurden (1)
I found corresponding bug in bugzilla - https://bugzilla.mozilla.org/show_bug.cgi?id=1004895
Can I vote for importance of this issue?