Orphaned project windows

I typically have two or three projects open at a time.  Since (I think) the update before last, when I close one of them, the window stays open, but blank.  Closing it again will close the first window opened.  If I try and open a new project in the orphaned window, and opt for "this window", it'll actually open it in the first window, replacing that project.

Windows 10, PHP Storm 2017.14.

   -- hugh