Somehow I have mananged to mess up my Materials editor UI and I can't find any reference on how to restore it to Initial state or fix it so I can see the windows I want to see.

Right now the preview window won't float or doc at all into the materials tab. 

I tried clicking on the UI dots, but they don't seem to do anything.

The manual and "help" text is not useful.

Edit - I attached a screenshot of my current materials ui