Avoid 100% CPU spin on IE9+ when the browser window is defocused while an Editor instance has focus, and then a different Editor is clicked to bring the browser window back into focus.   Fixes #16939 !strict.
Avoid problem on IE9+ where the link dialog opens then closes immediately the first time a link is double clicked.  It stems from a problem on IE9+ where the focusout event on the <iframe> comes after the focusin event on the <input> in the link dialog.   Fixes #16928 !strict.