My system is openSUSE 11.1 with KDE 3.5. I not infrequently copy URLs
and other text from a web browser to paste them into Thunderbird emails.
I would occasionally see cases where a copied item would not paste into
Thunderbird unless I retrieved it directly from Klipper. I use the
Opera browser for accessing and commenting a paricular web site, but I
use Firefox for general web browsing. Rather recently, I upgraded to
Opera 10.6, and I like it alot for what I use it for on that particular
web site. However, I have noticed that if I copy a URL and attempt to
paste it into a Thunderbird email, nothing gets pasted unless I click on
the item in Klipper. However, it will paste into KWrite without any
need to retrieve it from Klipper.

This does not happen with items copied from Firefox. In other words, I
can paste directly to Thunderbird without having to first click on the
copied item in the Klipper clipboard tool. Why the difference in the way
that Klipper works with the two browsers?