我如何创建一个帮助覆盖，就像你在一些Android应用和ICS中看到的那样?

I am wanting to create help overlays like the ones you see when ICS loads for the first time or in apps like ES File Explorer or Apex Launcher (there are more, but I can't think of them right now). Is this just a relative layout with one view sitting on top of the other? I haven't been able to find any sample code for doing such a thing. Anyone know how this is done or have any ideas?I am wanting to create help overlays like the o