Rectangle select > 'fixed ratio' does not work once the cursor gets outside the image boundaries
Screencaps to illustrate:
1) http://i.imgur.com/ohiLjZi.jpg- constrained to a square
2) http://i.imgur.com/4Er9Wpt.jpg- near the image boundary , still constrained to a square
3) http://i.imgur.com/X9jZlQp.jpg- once the cursor has moved outside the image boundary, the selection is no longer constrained to a square. The width of the selection should have 'locked' at a point equal to the height of the selection once the cursor moved outside the image boundary, but it carried on extending as the cursor was moved to the right.
