width 100% can makes child wider than parent

Have you seen this happen on an actual site? Would be nice to have a real world sample to reproduce the issue with.
As far as I can tell, the problems described in that article happen when the 100% width item has margins/borders/padding, but the editor doesn't use that on its wrapping span, so it should not get wider than the containing field-wrapper div.

Patch in #1 fixed CK Editor for me using the seven theme. Thanks

Saw a problem caused by this happen with the Bartik theme. The right edge of the editor got cut off by a div.
With the patch the editor stays within the div as it's supposed to. It can still be resized so the other div will obscure it, but it no longer happens on page load. The resizing problem is unrelated.

Committed this to all the main branches, -dev snapshots will be updated within 12 hours and this will be part of the next releases.

Thanks for the patch, Anders!
It got delayed far longer than needed and I'm sorry for that.