Okay so I figured it out. It turns out Event is defined within UnityEngine.IMGUIModule (see here for info)
For reference: If a type is unknown, you're probably missing a module.
I hope someone else is able to find this useful in the future. I am leaving this up in case it's useful. I have removed the original attachment as it's no longer necessary
For reference: If a type is unknown, you're probably missing a module.
I hope someone else is able to find this useful in the future. I am leaving this up in case it's useful. I have removed the original attachment as it's no longer necessary