Fading out the whole page in edit mode excepted the container on which you have some edition permissions

Mediasurface, another WCM, has a nice feature in edit mode. They are fading out the page to a light transparant grey mode excepted for the content objects on which you have some write permissions. The editor can then immediately identify which objects he can modify. This also better separate the edition mode from the preview mode.

I do not know if such a CSS oriented feature is hard to do (in such a case we will keep our borderlined containers) or is an easy one. Any hint?