title: How to create a global overlay for MacOS?
body: <p>I am trying to develop a MacOS application using Xcode and Cocoa. My intent is to create an overlay on the user's screen that is mostly transparent, and does not register input. For example, an application like f.lux tints the colour of your entire screen like a global overlay, but you can still click on-screen items, as mouse clicks go right through (assuming that it's an overlay). How can I get started with achieving a similar overlay/widget?</p>