How can I open a window on top of a full screened space?

I full screen a video in Safari.

I want to run some app that opens a little window on top of that full-screened video.

I don't mind what technologies I use to do this (AppleScript, some bash commands, python, Swift, Xcode, whatever) just wondering how Apple makes it possible.


It's simply not possible with current versions of macOS. You literally can't get a context without returning the full-screen window to a normal window.

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  • Well I have had it happen numerous times before, potentially a bug, but still possible. How do you know it's (at least meant to be) impossible? – theonlygusti Apr 19 '19 at 4:14
  • I said that as a developer. I tried to get a window context while a full-screen window was present. Whenever I managed to get a context, the full-screen window would get slid to the right and my window would appear on a different desktop. Obviously you can still draw atop the full-screen window, but you would need to bypass the OS to do so. Of course, that's with the standard API. It may be possible to hook classes all over the place and insert something but that would be a research project. It's always "POSSIBLE" even if you have to hook the graphics driver, but the effort will be great. – Wilfred Smith Apr 19 '19 at 4:49
  • What's your reason for putting a window atop full-screen Safari? If you just want to draw something simple and transient, that can be done without too much pain, but if you need an actual NSWindow, you're looking for trouble. There may be a better way to accomplish what you want. For example, it's possible to open an overlay window from the menu bar, but if you try to schedule any kind of complex interaction, you get a window or control on another desktop. – Wilfred Smith Apr 19 '19 at 4:58
  • How can i draw something simple and transient – theonlygusti Apr 19 '19 at 14:38

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