title: MS MVC login widget
body: <p><strong>Context</strong><br>
  In <em>LAYOUT</em>, i got 2 input fields and submit button.<br>
  If user authentication is successfully, i want to redirect him somewhere,
  if not - i want page to be updated with some validation text.  </p>
  
  <p><strong>Problems</strong>
  Cause widget is supposed to be located in layout, i don<code>t know which is current page, therefore - can</code>t get back on failed authentication (even worse - i know nothing about page state (changed fields, selected items in checkboxes, etc.)).  </p>
  
  <p>I could save state doing partial request on login form submit, but then - how could i redirect user on successfully authentication without javascript hacks?</p>