Users can actually use the "Find" from the toolbar menu. It's under the "Edit" tab.
To implement this functionality by custom code would cost you a really really long time in my opinion. Just quess if you want to search for a word also in textboxes for example.
I think you could may be achieve this with a custom button with code that runs through you underliying xml but I wouldn't do so.
Somebody else has a better idea ?
Listen to Motörhead cos they play Rock'n Roll :)