downcase-region in marked rectangle does not downcase entire rectangle
and downcases things not marked:
On the following content in my buffer (*scratch*), upon marking the
inner rectangle consisting of "FG" and "JK" using C-return (cua-mode
Applying `downcase-region` yields the following unexpected result:
I would expect "fg" and "jk" to be downcased, and not "fgh" and "ij".
Original report at http://emacs.stackexchange.com/q/9913/5154