Rated 5 out of 5 stars
This is a very handy extension. I, too, do not see the red outline of selected DOM elements, but that doesn't really hinder what I use this for. The only problem I actually encountered was what research (yes, i actually looked into this for several hours) indicates is coding for a status bar icon, as opposed to the Firefox 4 standard of being specific to the "addon bar". This made no difference as the icon still appeared int he addon bar, up until i used an extension that tweaked that bar (Minimize Addon-Bar), and it only showed addon bar icons. So, I lost access to SB+'s editor (was unable to access it through any other icon or menu) as long as that extension was active. Eventually I found a way to use "keyconfig" to hot-key the editor (botht the extension and the specific code for SB's editor (SB and SB+ use the same code) was provided by the author) so all is well again.
I would consider this a fault as Mozilla allowing items set as status bar icons to appear in the addon bar was only done to not break so many older extensions, and is rumored to only be a temporary allowance. As for my rating, I view this fault as only being worth about 1/4 star when compared to the benefits of this extension, so that will still keep my rating at 5 stars. :)