CSS resize on iframe

We have three panels on this window:
* Left: iframe with some simple text
* Middle: div contains pre (this text)
* Right: div contains another iframe
Default cursor is a plus sign.

Problem behavior: (with mouse events)
Resize left or right panels and release 
mouse out of resize icon. Resize event 
doesn't end, cursor remains pointer!
Resizing continues until a mouseup 
event on one of the resize icons.

Problem is not observed on this panel.

Click on the checkbox for a quick fix:
You cannot release the mouse out of the
resize icon and the problem is solved.

To reproduce the problem behavior:
1. Select some text in the middle panel (cursor is plus)
2. Resize the panel on the left and release the mouse outside the resize icon (cursor becomes pointer, indication of the bug)
3. Try to select some text again in the middle panel (you cannot select, the left panel is resizing)
The most important thing is to drag outside the resize icon, not just a click)