Operating system: Windows-10 64 Bits
Graphics card: GeForce GTX 1050 Ti latest driver
Broken: version: 2.80.71 hash: 828efef15175
Short description of error
Fullscreen Area Button conflicts with Sidebar top row...this should be fixed before UI freeze, probably best to bring back those arrows in the 2.79b and put them in the bottom right corner.
Exact steps for others to reproduce the error
Toggle fullscreen area in the viewport (Ctrl+alt+space) and try to click in the top right corner in the n-panel location bar.