Mysterious Button

I'm still learning how to use the technology in my car.  A few days ago, I noticed that the part of my navigation screen that usually shows the current time, the radio station/song information, the distance from my destination, and expected arrival time had disappeared.  Fortunately with just a couple minutes with the owner's manual I figured out that I had pushed the big-ass button on my console while the nav screen was active, turning off that information, and all it took was pushing the button again to make it reappear.

But this morning was really confusing when a few minutes after leaving work, a strange rounded-corner square with some contrasting edging appeared on my navigation screen.  It looked so much like some kind of control button that I actually pushed the screen before I remembered, Um, duh, my system doesn't have a touch screen.  (Robert's car does, and I've used his system more than mine, so it's an ingrained habit.)  I couldn't figure out what it was for.  A minute or so later I looked again, and the "button" had changed position on the screen.  Huh?  So I looked at the position of the "button" on the screen relative to the map on the screen, and looked out the window at where this "button" would be if it were part of the map, representing a real world object, and not some part of my information system floating over the map (like the time/radio information discussed above).  Oh, hello.  It's the football stadium they've been rebuilding.  It hadn't been represented on my map before, but I guess it's done now (yep, it's done, according to the team's web site) and it's back on the map.