A situation I notice regularly is triple clicking the last line of a post, and then trying to do the Quite Reply. But triple clicking seems to select enough extra blank space that
My guess is that essentially selecting the last line and the “return” means that the selection extends outside the bounds of the message and thus disables the “quote reply” feature.
It would be nice if this could be special case/handled so that selecting the last line of the reply including the end of that line still worked with the “quote reply” facility.