Why doesn't draggable containment work here (jsfiddle)?

Why doesn't draggable containment work here (jsfiddle)?

I'm trying to create a containment div which will hold some draggable divs. When the draggable is placed in a corner of a percentage-sized container, you can resize the browser window and get the draggable outside of its parent's bounds. The containment works once you start dragging again, but in some cases like when overflow:hidden is set on the container this can get your draggable where you can't click it.

Here's a little demo of what I mean, just move the blue box to the right side of the container and resize the window. http://jsfiddle.net/ppzgT/1/

Also I've been searching for an answer to this for hours, and came across this bug report stating the issue was fixed years ago. But I can't seem to find anything else about overcoming this issue. Thanks for any guidance you guys can provide me!