Sit-Target Teleports... Not Quite

Okay, so everyone knows about sit-target teleporters... handy little items, for TPs up to 300m. But they do require you to right-click and sit on them. I have, however, seen things that look similar... a group of signs for various floors on a store, for example... that you don't right-click and choose 'sit' to use; just touching them (left-click) is enough to send you to the destination.

So... how's that little trick managed?

When you're editing an object, you can select the default action for a simple left-click; "sit" is there as well as "buy" and "open" and a few others along with the default click. Look at the bottom of the editing widget, either on the first or second tab (not in world to check which one).

Thank you. I've never bothered to look at the "default action" drop-down before.