Oh wow great, I hope this works for me too! I have an LG 4K screen and the LG tool to change brightness and contrast is really terrible, it has some stupid built-in fake Picture in Picture mode which is constantly flashing red borders around the screen when you use it. And the UI is really bad and slow.

This little menubar control looks like just what I wanted.

Edit: Yes it works great! On my LG24UD58. Perfect! Unfortunately it doesn't seem to work with my Eizo L568 but that's ancient. And I think it had some special USB-based control method. But really glad to be able to get rid of the LG software now.

PS: You have to enable the contrast with a tickbox, otherwise that slider is not shown.