Thanks for your series on GIMP, I've always found it hard to use and I think this is going to clear up some of my issues.  In this episode - I'm thankful to learn that layers have "modes", I didn't know that.  I think that's my main problem with GIMP - it has functionality I don't know about, and sometimes I end up in these other modes and all the commands do unexpected-to-me things in those modes.  So now I know to watch out for these layer modes.  I'll have to try it out!