Where is the KDE widget directory or how to edit "Picture Frame" to show other "Pictures of the Day"

Hi,
i need help finding the “directory” of the KDE (plasma-)desktop widgets. My goal is to edit one of the default widgets, namely the “Picture Frame” widget.
This widget is for displaying pictures or slide shows of pictures, and it has another option called “picture of the day” this allows to show the “picture of the day” of one of a very small list of web services (wikimedia, some astronomical and geographical service, and so on).
What i want is to “add” in some way an additional “website” to this list.

Of course i do not know in which format those widgets are stored but i hope it is some kind of easy readable and modifiable scripting language.

So basically my problem is maybe not just finding the correct directory but maybe an additional hint on how to start changing/creating widgets (i do not want to create a fully new widget i really just want to change a present one or use it a a basis for my personal use)

I doubt you can get a ‘directory’ because this is a rapidly developing resource but you may find starting at http://forum.kde.org/viewforum.php?f=67 will get you the answers you want.