TIP: What does that "dash" mean?

I'm sure you already know that if you look under the Window menu and see a check mark beside a palette, it means that palette is currently open, right? OK, so what does it mean if you see a dash beside it (like the one shown here--click on the image to see a full-sized version, so you can see the dash) instead? Believe it or not, that's Photoshop's way of telling you that the palette is open, but it's hidden behind another open palette. It doesn't mean it's a tab, nested with another palette. It literally means (in this case), you've moved some palette in front of the Info palette on screen, so the Info palette is totally hidden. See, doesn't that make your day just a little bit brighter?