Pressing F1 (the Hide GUI shortcut on Windows 10) will not consistently work correctly, and you can end up with only part of the GUI showing or being hidden.
Steps to Reproduce
-Press F1 notice the quickbar still shows
-Press E twice to open and close inventory notice the GUI is hidden now
-Press F1 Notice that any tool in hand shows, but not the quickbar
You can also find that sometimes the quickbar will appear empty also. Scrolling the mouse wheel will also make the gui show up properly if it's hidden.
Additionally, pressing F1 or choosing 'Hide GUI' doesn't work when you are riding a boat.