Treat alt-(arrows/pgup/pgdn) like alt was not pressed. There's no reason to ...

chrome/browser/autocomplete/autocomplete_edit_view_win.cc

 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/autocomplete/autocomplete_edit_view_win.h"
 
 #include <locale>
 
 #include "app/gfx/canvas.h"
 #include "app/l10n_util.h"
@@ skipping 1647 matching lines @@
       model_->AcceptInput((flags & KF_ALTDOWN) ?
           NEW_FOREGROUND_TAB : CURRENT_TAB, false);
       return true;
 
     case VK_PRIOR:
     case VK_NEXT:
       count = model_->result().size();
       // FALL THROUGH
     case VK_UP:
     case VK_DOWN:
-      if (flags & KF_ALTDOWN)
+      // Ignore alt + numpad, but treat alt + (non-numpad) like (non-numpad).
+      if ((flags & KF_ALTDOWN) && !(flags & KF_EXTENDED))
         return false;
 
       model_->OnUpOrDownKeyPressed(((key == VK_PRIOR) || (key == VK_UP)) ?
           -count : count);
       return true;
 
     // Hijacking Editing Commands
     //
     // We hijack the keyboard short-cuts for Cut, Copy, and Paste here so that
     // they go through our clipboard routines.  This allows us to be smarter
@@ skipping 583 matching lines @@
 }
 
 void AutocompleteEditViewWin::RepaintDropHighlight(int position) {
   if ((position != -1) && (position <= GetTextLength())) {
     const POINT min_loc(PosFromChar(position));
     const RECT highlight_bounds = {min_loc.x - 1, font_y_adjustment_,
         min_loc.x + 2, font_ascent_ + font_descent_ + font_y_adjustment_};
     InvalidateRect(&highlight_bounds, false);
   }
 }