title: gtk_window_fullscreen problem
body: <p>I need in full screen window functional in my gtk+ application. I try to use <code>gtk_window_fullscreen(GtkWindow* Window)</code>: </p>
  
  <p>I have function:</p>
  
  <pre><code>static void
  full_screen(MainWin *mw)
  {
      gtk_window_fullscreen((GtkWindow*)mw);
  }
  </code></pre>
  
  <p>When i try to call this function i see error: </p>
  
  <pre><code>Gtk-CRITICAL **: gtk_window_fullscreen: assertion `GTK_IS_WINDOW (window)' failed 
  </code></pre>
  
  <p>Where MainWin:</p>
  
  <pre><code>typedef struct _MainWin MainWin; 
  
  typedef struct _MainWin 
  { 
      GtkWindow parent; 
      GtkWidget* scroll; 
      GtkWidget* box; 
      GtkWidget *toolbar; 
      gboolean full_screen; 
  };
  </code></pre>
  
  <p>What's wrong?</p>
  
  <p>Thank you</p>