Preview opens multiple pdf's in same window
Since upgrading to Mavericks, Preview frequently (but not always) opens pdf's in an already open window. The preferences are set to open each pdf in its own window, but that is being ignored. If I could easily separate them, it would not be such a problem, but I can't find a way to do that. How do I fix this annoying bug? Thanks
MacBook Pro, Mac OS X (10.6.3)