title: access to focused element from background page in extension for Google Chrome
body: <p>I am developing an extension, that should change contents of focused text input element on the web page.</p>
  
  <p>So my extension has a background with some function, that gets the text that needs to be inserted to last focused html input element. The problem is in getting such element. In FF it is document.commandDispatcher.focusedElement I tried to use window.document.activeElement, but it allways returns object of background's html body, and not current window's object. (But in documentation is said that "In the case of the background page, the value of the current window falls back to the last active window...")</p>
  
  <p>So the question is, how to get the current focused element from a background page of the extension?</p>