How to trigger on the appearance of an app's context menu?

I want to automatically select an item when a context menu appears. I can use the "trigger context menu item" to do the selection...

How can BTT recognize the context menu has appeared, so it can then make the selection?

I'm clicking the download icon for a Mac Mail attachment, which brings up a context menu with options on where to save it. I always save to the same location, so want BTT to make that selection for me. -- If I need to manually trigger BTT to make the selection, I may as well move my mouse to make the selection manually.

I'm considering trying to Find/Search Image On Screen of the menu's pixels, but that hasn't been particularly reliable for me when I've tried it in other cases.

Thx

Turns out my idea of using Find/Search Image won't work, because it's not a BTT trigger, it's an action. I could trigger BTT with the mouseclick that brings up the menu, but it's a one-finger click which is not an available trigger.

So I'm still hunting on how to do this.