Since "Better copy to clipboard feature. - ID: 2880712" there is a Flash plugin that should copy the password to the clipboard.
Not all people have Flash, and even current gnash doesn't work with that SWF file yet.
So please, on "show password" write the password without whitespace - then a simple double-click on the word is enough to select it.
Currently the spaces before/after the password get selected, too - and then pasting doesn't work, of course.
Thanks.