Based on your feedback, I updated the mockup from yesterday (V27Nov17) for a new feedback round.
Changes:
- Dark grey changed to #2e2e2e (madsrh) from #252525
- Unfocused Window now #414040 (madsrh) instead #3f4140
- Different windows min/max/close buttons based on United theme (madsrh)
- No round corners on the bottom anymore (because overlapping elements problems)
- Less round corners on the top
- Window boarders reduced from 2px to 1px
Login V29Nov17
- didrocks pointed out, that we can not change the background for the screen (“This was the reason we selected this purple color + noise in 17.10”) so maybe we can use (css?) to create something fitting to the design based on the dots Ubuntu was using? Please give it a try! I would like it to be not too dark like here, but the background should also be not too present.
Test with background texture (https://www.transparenttextures.com/light-sketch.html)
Main Desktop V28Nov17
Files Window V28Nov17
- Back/forward buttons with no boarder again
- Breadcrumbs change to fit the design with a slight background color for active elements like on the dock (wfpaisa, godlyranchdressing, and madsrh)
- Changed content background colors to Ubuntu default
Files Windows Overlap Test V28Nov17
Files maximized Window V28Nov17
Terminal & Calc Test V28Nov17
Waiting for your feedback and change proposals! 
Please compare also the previous version.