Keep a UI.Image from blocking Clicks?

I figure this has been asked before, but my googling has not found an answer. I have a border for a menu screen with a large transparent area in the middle. The border has elements that I want to show on top of the menu elements.

However, the border -- being transparent even -- blocks any clicks on the menu.

Is there a way to show the image on top without having it block any clicks? I see the "intractable" boolean for other UI elements, but not for UI.Image.

Thanks!