I've had my keyboard shortcuts set up so Ctrl+Tab gives me my next editor tab, Ctrl+Shift+Tab moves back one. The tab order is based on the list at the top rather than most recent or anything like that.
A little while ago (maybe 3 months?) when I Alt+Tab out of PhpStorm then come back to it, sometimes Ctrl+Shift+Tab will actually open the previous tab in a new window, rather than in the same window (see attached screenshot). The file stays open in the main window, but also opens in a new window. I've tried looking through my mapped shortcuts to see what else is mapped to Ctrl+Shift+Tab, but there's nothing else mapped to it.
Has anyone seen this before, or have any idea what might be causing it? I'm running PhpStorm 7 on Mac (Mavericks).