Hi,
is there a way to create a widget ourselves? Any documentation?

I have a set of design steps to make a slide popup and show when clicked and I'd like to automate this. Is this possible? So I can store it in the widget list and just drag&drop it onto a page and then just drop a picture on it and it would apply saturation, shadow, transparency, onmouseover, onclick, etc... automatically, the way I want?
Since I have about 300 pictures, I'd prefer not to do this manually for each of them.

Thanks for any help.
(The current slide widgets don't do what I need, that's why I'm asking, so thanks for not telling me to use a prexisting slide widget).