[GUI] Programming without form

Hey people!

Maybe you know the program Ukagaka?
(en.wikipedia.org/wiki/ukagaka)
Or maybe the good old eSheep?

I have a small question about the graphical engine. Both programs work without the normal rectangular windows forms. I know how to show a static unnormal programform (ew... my English..) but I don't know how to program such animated programs. I could imagine an engine with DirectX, but I don't think eSheep uses a big DirectX engine. Ukagaka uses an engine which is even able to draw single pixels on the surface over all other programs...

What I wanna ask is, how can I draw pixels where I want? Even over other programs...

I mean, desktopsidebar is able to do so, too and so on...

WEll, I hope you know what I mean

Well? Did any of these suggestions help you? Don't just come and take from /prog/ and not give anything in return.