Okay. With that simple concept by @alexcr I have a kind of solution.
It just uses the Keyboard Maestro "Click at Found Image" action. I took a screenshot of a selected area of the blue highlight colour that appears around selected items on a Mac. For some reason, each app needed a different screenshot of its own specific blue highlight colour which is why the Macro has different Switch/Case Actions - one for each App.
To add more Apps to the list you would duplicate the Switch/Case Action and then paste in a new selected area screenshot of that App's highlight colour into the Image Well in the Action.
And you would need to add in the App's name in the conditions.
This Macro might just work for you as is - or you might need to make your own screenshots of the Blue Highlight Colour for each specific App as they might be different on your Mac.
I've only tried it on one of my Macs so I don't know if it will work as expected on them all.
