Hi Michael,

sorry for getting back to you so late.

I think the new look fits MoIs overall style better.
I'm not sure about the divider line though. I think BurrMan is basically right: Normally if you use tabs, the opened tab has no dividerline towards the open area of the tab.
But I tried it out in Photoshop, and without the line the heading is pretty weak...

And somehow I am still missing consistency with the rest of the GUI (which I like a lot).
I'm not sure if you need to introduce new elements at all.

So I went to explore the existing elements some more in Photoshop...

First I created a header for the Scene Browser (without a + sign) that would be collapsible like the other toolboxes to be consistent there.
In this form it doesn't take much space when collapsed (see the top of the image below) and I think that one line doesn't take away too much screen estate while it helps the overall consistency. Also, you can collapse the Browser with one click, equal how many of the sub-tabs are open.

Then I took the existing idea that you use in the headers of all other toolboxes and played with them. They aren't exactly "tabs", but work very well for me as headers for the toolboxes.
Putting them completely inside the existing frame of the scene browser would create a doubleframe which would be a bit overdone, so I tried using the rounded corners "connected" to the outer frame directly and well - works for me and fits in pretty well with the rest of the GUI IMHO ;-)



No new elements needed, the headers are clearly visible and divide the groups very well while being light on the eye and no problems with the tab-divider-line.
I also wasn't too hot on the light blue header color (again more a consistency thing).

What do you think?

Best Regards!

Thomas

P.S. I think Pilou brings up an interesting point. Being able to create hierachies of named objects (move the parent and it will move the child as well) like it works in many other 3D tools could be helpful. Also having some basic "file-like operations" in the right mouse menu would be interesting (copy, paste, delete...).