title: Bootbox, two modal windows - one above another
body: <p>I have two bootbox modal windows - parent and child.
  If user enters wrong data and try to save the parent modal window, the child window appears.
  The problem is - when the child window appears, it's still possible to click on the parent modal window buttons.
  How can I fix it? The parent window controls must be disabled when the child modal opened.</p>
  
  <p>Thanks a lot,</p>
  
  <p>Michael</p>