Can you add an option to see a replay of the brushstrokes like on other oekaki boards?

Not unless somebody writes me some code for this, I have no idea how it works.

I can only assume the user's inputs are cached from the "undo" pile in the editor during saving and upload. Then re-input through some sort of time lapse on a read-only oekaki canvas when an animation request is clicked on. Like clicking on undo from the last input to the beginning and then redo to see the progress. I guess animating each stroke as it happened could be troublesome to implement but a simple redo slideshow sounds doable.

I don't think the Shi Painter Java app can save animations. It's not something WAHa can implement, because the Java program itself doesn't support it...

By the way, Lascaux might be something worth keeping an eye on...
http://cellosoft.com/sketchstudio/

look at http://fearsome-oekaki.com and the program it runs: http://www.ninechime.com/products/

You should be able to add animation and the ability to continue pictures..would be very nice.

Hmm indeed... The relevant parts of the code seem to be in "shiget.php," If I'm looking at this correctly... Perhaps it is possible after all.