Well, it seems like it was created for the launch of Developer Edition v44, so that would have been when the stable release was v43. The current stable release is v44, so in theory everything in this demo/tutorial should work with current stable. I found a couple things didn't, though. I couldn't get the CSS eyedropper tool to apply the color I clicked on; however, manually entering the hex code for the new color triggered the completion event. I also couldn't get the event to fire in the second-to-last task.

Regardless, it's a neat little distraction to do while eating lunch.

edit: clarification

No, Developer Edition version 44 releases today. Stable will be version 42 after the release.

Yep, my mistake. Erk...

Developer edition is 2 versions behind stable, not one. (it's the old auora, rebranded).

firefox 42 is released to stable today.

nevertheless, I do see some of the new animation controls on firefox 42.

I noticed a weird behavior with the eyedropper but it did work, partially. For me, it worked when the inspector was side-docked in the window, but not when it was free-floating.

That's not correct, though, I went through the whole thing just fine with regular Firefox.

Same here -- running regular FF here

Ok, let's add that to the title.

It works with regular Firefox, though, I just did it. Maybe OP needs to update their Firefox?

Ok, let's take that out of the title.

I simply don't understand why to have separate Developer Edition instead of making available the devtools in stable FF only? Easy to maintain.

Firefox's devtools are available in all maintained versions of Firefox. Why would Mozilla restrict devtools to releases? How would people test the devtools in that case?

Marketing. Chrome DevTools has a much bigger market share.

Plus obviously you're not a real hacker unless your software is light-on-black.