It is not as beautiful as I would like, but I have made an Add or Subtract Fractions Tool
Does it work for you?
Now my only worry is that students may use it to do their homework - but hopefully they will learn the method.
I've tested it out a little - Yep, it works. I see no bugs.
As Devanté says, it looks bug-free. Sometimes there isn't enough space for it to write all the numbers in, but that's just because I was being silly and trying out huge numbers on it, so it's not a problem really.
Why did the vector cross the road?
It wanted to be normal.