I think we can remove modal dialogs and replace it with a "undo" or trash system. Specially when you delete something (node, menu, bloc, etc).
They have a great article about that at listapart See http://www.alistapart.com/articles/neveruseawarning/
Gmail have this kind of undo and recently add "undo send" http://gmailblog.blogspot.com/2009/03/new-in-labs-undo-send.html .
Some issues about modal dialogs
- "Popbox (Popups Lite): Adding Modal Dialogs to Confirmations" http://drupal.org/node/374646
- "Warn before losing changes (eg: blocks and menu admin pages)" http://drupal.org/node/193799
- "Popups: Adding the core modal dialog API" http://drupal.org/node/218820