Getting an all black background in full screen mode on macOS

Changing the theme to one with a black background isn’t enough.

For some reason, TeXmacs has a nearly white line at the top in full screen mode that serves no purpose.

Moreover, the vertical scroll bar is very bright and always visible.

The horizontal scroll will be there as well if you have a line in your document that won’t wrap at the screen edge.

I think fixing these issues would make TeXmacs nicer to use with a dark theme, especially when taking notes alongside another app in full screen mode on macOS.