If you were to have 2 windows open, currently both windows would have a sidebar, which is kinda redundant and in the way. This fix would let automatically detect which window is closer to the edge of the screen (the left screen if the sidebar is on the left, right if on the right) and only display the sidebar on that window while hiding the sidebars on the other windows.
This will just make it a lot more convenient to use 2 windows side by side.