I've asked a question on stackoverflow and found that i should report this one because it's probably a bug.
So, i work on Mac OS 10.9.2 with Qt 5.2.1. In my project i use QDateTime widget with popup calendar. And it looks like (both in QtDesigner and working app):
As you can see white area is higher than arrow and it looks pretty ugly. This problem occurs when i set "calendarPopup" option on "true" (in QtDesigner).
Same project under Ubuntu 13.10 looks like:
I've found that if i set style sheets on "border: 1px;" QDateTime became:
but on SO i've got an answer that style sheets drops native platform styling of widget.