how many buildings? There's a somewhat labor-intensive way of doing this with "invisible buttons".
You'd create a separate button that is transparent, and "brought to front" over the container with the map, and sized to cover the building. Then you'd show the image of the underlying building via script, or the button's single-step.
p.s. this method is not so good if your map image changes often.
If you can open the map in a web viewer, there are probably ways to do what you want via Java Script.
If you are using FM GO with an iOS device, you might be able to use the OnGestureTap trigger to both perform a script and capture the coordinates of where the user tapped to figure out which location on the map was selected.
Thanks David!!! Your suggestion fixed the issue. The map won't change that often, so not an issue.
Thanks to those that replied!