If we forked xkbd into the library it would use the library's theme system to draw the keys as buttons. The keyboard would of course be a widget and thus the theme could apply a unique style to the keys to make them look different from other buttons in the theme.

Does xkbd only allow you to define one row of keys per instance? If we fork it, our version would allow an entire layout to be defined in one file, positioning the keys inside automatic layout boxes. Each layout could also have one definition that handles both landscape and portrait or separate definitions for each orientation.