Is there a way to remove the gap between window edge and the screen edge when the Dock is hidden? When you hide the Dock, OS X leaves a small gap at that edge. Is there a way to get rid of it?

In case you have never noticed the gap before here is a screenshot. Guess which side of the screen has the Dock:
Not yet (as of macOS Sierra 10.12.6). When hiding the dock, the OS still leaves ~4 pixels of visible space presumably reserved for some part of the dock behavior. Third party window resizing doesn't seem to help either. Creator fifafu of BetterTouchTool wrote:


  You mean the gap when the dock is hidden? Unfortunately this is a
  limitation given by the system :-(. I haven't found a way to
  workaround that.


Note: This is more noticeable on lower resolution external displays (4px on a retina display is barely visible). 

Some workarounds:


Move the window over the visible pixels, then drag from the opposite side (but also notice the additional delay in showing the dock)
Use an external display and set a different monitor as primary (drag the white menubar in the display arrangement in sys prefs), allowing full sizing on the non-primary display.


Related Apple SE but for visible docks: Force windows to be maximized but not fullscreen?



Have others noticed? Yes, lots. Macrumors dead ends:

https://forums.macrumors.com/threads/bottom-dead-space-with-automatic-hidden-dock.1716910/
https://forums.macrumors.com/threads/hiding-dock-still-leaves-a-few-pixels-unused.1208427/
https://forums.macrumors.com/threads/how-to-remove-space-between-window-and-dock.1094679/
https://forums.macrumors.com/threads/hidden-dock-small-space-in-the-bottom-of-the-screen.931858/

It's even caused bug reports for OS X app developers:

https://github.com/eczarny/spectacle/issues/555
https://github.com/fifafu/BetterTouchTool/issues/672
https://github.com/search?q=mac+dock+gap&amp;type=Issues&amp;utf8=%E2%9C%93



I'll add that this issue exists vertically as well:





Manual workaround