improvement: enable "from bottom right to top left" selecting in editors

[esaruoho]

Steps to replicate.

1. Select bottom right corner, hold mouse button down, move cursor to top left corner

expected result:
just like with top-left-corner to bottom-right-corner works, bottom-right-corner to top-left-corner works.

current result:
bottom-right-corner to top-left-corner selection does not work