Smear FX is a program designed to help you with animation editing. With it, you can modify the initial state, movement, trail and general aspects of your moving image in the smallest of increments.
At first glance, the application doesn't quite seem like a professional tool. With its pixelated interface and bright colors, it seems more like some page out of a comic book rather than software designed for editing.
If you get past the first impression and take a better look at it, you will see that it's far more complex than you may have given it credit for. There are a lot of fine details that can be easily tweaked using the mouse cursor in order to obtain the result you desire.
After using it for a bit, you can see that Smear FX can be used either to refine your animation with small changes or to make them completely different. At any point, you can test your changes by actioning the Simulate option.
If you decide to try out the entire animation and have it play out, you can also use the Render option. While it is going on, you can also see the frame count, the current frame at which the animation is at any given moment and also the zoom, all on the same canvas with the animation.
If you do not have anything planned and just want to try it out and see how it works, you have over a dozen examples to see how it performs.
The program is interesting, and its cartoony aspect also makes it fun to use. If you are not sure you want to invest in it, you can just try out the demo version and see how you like it. If you are passionate about animation and graphics, you should at least test it.