What "user" must a scheduled task run as in order to be visible for all users?

I wish a task to be scheduled to run when any user logs on, but is not dependent on any one user being logged on, so I pick "Run whether user is logged on or not". The problem with this is that the program runs hidden (as stated in the docs and queried in this Microsoft Community post), but I need the GUI to be visible.

So, I need to pick "Run only when user is logged on" for it to be visible. But any one "normal" user might not be logged on!

Which user account should I use in order to run this task?

I tried running it as SYSTEM, but that automatically sets the "Run whether user is logged on or not" option - so it will run hidden.

I just tested this and you can select a "group" for the account.

Pick Run only when user is logged on.

Click Change user or group (it says group right there :)

type in users and click Check Names and Click Ok

and you application will run interactively for all users in the group users.