just a note regarding the "full-contents-tooltips": you can't mark
anything in a tooltip. why this could be a problem:
imagine, you have some program, that internally requests ultra-long
urls. now a messagebox appears "weird error processing
http://this.is.long.no/cgi-bin/script.php?[...]haste+nich+gesehen".
as you can't mark it, you'll have a real problem checking out by hand,
what's wrong ...
maybe, in that case just logging the error with the full url is the
correct solution, but there may be other cases.
so after all i think, it's not good to squeeze anything. breaking long
"words" for displaying and hacking the selection code to not put the
automatic linebreaks into the clipboard seems more sensible to me.

greetings

-- 
Hi! I'm a .signature virus! Copy me into your ~/.signature, please!
--
Nothing is fool-proof to a sufficiently talented fool.