I've upgraded my machines to RDM Enterprise 13.0.1 from 12.8.0 and the Classic UI theme looks identical to the 'Default (Menu)' theme. Is this by design or a bug? 
Hi,
Unfortunately it's by design. I had to rework the internal architecture and it was not possible to keep the original Classic UI. I've tried to make the current UI similar to the Classic UI but it's not exactly the same.
It used to be based on MDI and it was causing a lot of issues. What do you miss exactly from the Classic UI?
Regards
David Hervieux
That's a shame. I was afraid this would someday come, and I do appreciate you keeping the Classic UI for as long as you have. I am just not a fan of the DevExpress window decorations, especially the title bar which is several pixels taller than it needs to be and inexplicably grows another couple of pixels if you maximize the application. I just wish they offered something thinner for those of us who wish to conserve screen space.
Cheers, David. I appreciate your efforts.
-Rico
I will check what we can do to reduce the UI wasted space.
Regards
David Hervieux