title: save a file generated by a php script in to a directory by save dialog form
body: <p>I have a php script that generate a pdf file.
  So I have an html page with jquery javascript that do an ajax call at this php script and retrieve the pdf file content.
  I would that this file will be saved in a location choosed by a save file dialog.</p>
  
  <p>How can I do it?</p>
  
  <p>Thank you so much.</p>