Hotspot Outline??

The easiest trick for this is to create an actual shape (rectangle, circle) but leave it unfilled. Set the outline color to what you want (red, black...) at about 1-pt thickness. Then put the hotspot in that shape.

You may want to shade the fill of the shape with a very light gray to make it even more obvious, if that's what you're trying to do.

You might also try using markers, but you don't explain what you are wanting to accomplish, so perhaps that's a bit of overkill.

skrap2000 : Instead of hotspots, I like to use a shape with a solid fill that is 100% transparent. 

The advantage of using shapes is that you can add states, such as Selected and/or Visited.

The main drawback of that method is that transparent shapes aren't visible during editing (like hotspots are). However, they certainly would be if you include visible outlines.