This GIMP trick is in a video format and is up on YouTube for you to watch. It was just easier to let you see my screen that way.
I was watching other GIMP tutorials on YouTube, and stumbled upon this trick, but when I tried it out the next day, cause toggling on and off visibility to layers is a great feature, I realized that I usually leave a lot of layers in my projects even though I don't want them visible. So I decided I better test this new trick before using it in my project I was working on. And I'm glad I did, cause there's something important that I had to figure out how to do.
Let me know if it was helpful for you.
NOTE: you can watch it directly on my blog, but an iPad it didn't show the YouTube notes on the screen, so if something is confusing, please click through to YouTube and see my notes there.