Adds the standard MacOS space bar shortcut to the Unity Editor Assets menu.

Sends the paths of any selected assets to the qlmanage app:

https://developer.apple.com/library/archive/documentation/UserExperience/Conceptual/Quicklook_Programming_Guide/Articles/QLDebugTest.html

qlmanage -p /path/to/Unity/Project/Assets/triangle.fbx

A complete bodge, as the qlmanage app was really only supplied to be used for debugging QuickLook extensions. But it works: you get a nice QuickLook-style preview window, even with multiple asset files selected.

(I’m not even sure if qlmanage comes as standard on MacOS, or if it’s only part of the extra installs available through Xcode.)

I used it for years on systems up to and including Catalina, and it seemed happy enough. I always wanted to check it out on more recent versions (Big Sur and above), but never seemed to get around to it.

Depending on circumstance, I would sometimes have it assigned to the backtick (`) key on my keyboard (rather than the space bar), simply because sometimes I found the backtick key location more convenient on my keyboard.

But most of the time the space bar has been okay: space to QuickLook preview an asset, space to close the preview and return to Unity Editor.