SSMS 2014 (and 2012) CTRL+TAB requires pressing enter
To fix this issue: Tools \ Options \ Keyboard.  Bring up the command in the "Show commands containing:" list.  Then in the "Press shortcut keys:" text box press CTRL+Tab and click Assign.  This will re-assign the command back to itself, but fixed the "sticky" window.  Just had the same issue. Hope this helps.