What I did was use a trigger sprite in front what I wanted to interact with. So lets say there was a sign I wanted people to read. I would place the sign and then I would place a transparent sprite, in the location the player should be standing when they want to read the sign. I used to an event similar to this:
If Player is overlapping TriggerSign06
And Presses KeyboardButton A
You would really only create one pop up window and then, based on which trigger was triggered, you'd send in a string of text.