This mod make fullscreen windowed fullscreen(aka borderless fullscreen).
What are advantages of windowed fullscreen?
1.You can display a window set to the forefront on top of Minecraft.
For example, you can play minecraft while watching YouTube with Chrome picture-in-picture.This may be useful for building while watching a reference video.
(Windowed Fullscreen,Google Chrome picture-in-picture Youtube)
2.You can see IME candidate windows with CocoaInput on Windows.