It is technically possible to have the tabbar appear inside pages, but unfortunately it's not possible for every type of page (e.g. not on chrome://* pages, http://*.png, ftp://*, ...); and that is the main reason I didn't take that approach. That and the fact that it would take significantly more resources to draw/maintain a tabbar within every open tab.

The real proper fix for the issue you describe is for the Chrome team to implement a true sidebar API for extensions to use. They had one mostly working in 2011, but decided to cancel the whole project and delay the implementation until 2013 soonest. Given that, I decided a "best approximation" solution would have to suffice until then.

Assuming you're on Windows, a possible partial solution for the resizing issue is just to maximize the docked-to window whenever you want the maximized effect. I agree it's not pretty having two windows open, but at least you can get a decent approximation of a true maximized-window-with-sidebar that way.

If you have multiple monitors you might also try turning off the "allow Sidewise to unmaximize the dock window" option and see if that suits you.

I like the black/theming idea, and am marking this issue as "planned" until I get to implementing a proper theming system. It's all just CSS driven styling so it should be pretty easy for myself and others to produce new themes.