I think that's pretty crucial for it to succeed and be something more than just something you put your kid in front of and turn on the DVD. We wouldn't have got involved if it were just for little kids. We wanted to write something that works on both levels.

As an actor going into screenwriting, I was able to understand what type of dialogue feels natural. A lot of the time, as an actor, you don't have the freedom to change what your lines are, and they can often be very unnatural or difficult to portray in a real light.

I think that's pretty crucial for it to succeed and be something more than just something you put your kid in front of and turn on the DVD. We wouldn't have got involved if it were just for little kids. We wanted to write something that works on both levels.

Another thing that makes the process different is we go in there and are completely immersed in [that] world for however many weeks and then we would leave and they would be animating for however many weeks and we wouldn't have anything to do with it. Then we would come back and see all this work that they had done. So it just took a lot more time than it would on anything else.

We always for better or worse try to put on paper what's going up on screen - whether we're directing it or not. It's really just an extension of that habit which is trying to tell the reader what the movie will look like. Ultimately that is the job of a screenwriter to a certain extent.

It's like live action if you reshot every scene a million times after finishing the movie. Because even apparently by the very end, a few weeks before they were screening it for the world premiere, they were making changes. That's just simply something you can't do on live action.

I had always been interested in screenwriting, ever since I could write things down as a child. Obviously, I started as an actor, professionally, but screenwriting was always something that I had a great interest in.