after searching somewhat more on keyloggers it seems that newer (key)loggers might possibly detect mouse operations (not sure about exact mouse positions/clicks , but depending on the program it could also be possible)
however , simple (read: older) keyloggers that log only keystrokes would logically be "tricked" with the random-letters trick described in my previous post
more in the wikipedia article on
Keystroke Logging
seven - copy&paste does protect against the simple keyloggers that just log keystrokes
2 things ...
a. a website can retrieve what you have in your clipboard
go to
http://hexillion.com/co and click on Browser Mirror to check what your browser reveals
(when I went some years back with IE5 or IE6 the clipboard field was populated with the data I had in my clipboard , today that I went with IE7 I got an IE pop-up whether I wanted the site to access my clipboard , to which I pressed Don't Allow)
b. check the wikipedia article at the top of this post ... both the random-letters and the copy/paste tricks are mentioned in the Non-technological methods of Keylogger prevention (Non-technological methods is the last paragraph of the article right above References)