Thanks for the kind words.

The skin.c is a good idea. I can make it be usable as a header script that is included at the beginning of the main script for all who want to use the default skin.

Before I'd make an editor, I think it would be useful to make an XML-like syntax for defining GUI elements. Then I could make an editor that creates those XML files. Those files would then be easier to be reopened by the editor.
But if I can ever do that it will be in the far future...

An improved API and multiline text fields will certainly be part of an update some time.