There are two levels of user interface customization:
1. You can change all colors using text configuration files and you can also replace the icons with custom ones.
2. If you want to customize it more, you can write your own drawing code and replace our standard user interface classes/widgets. But this requires ObjC programming.
Could you perhaps let us know how the GUI should look like? Of course we want to keep the basic paradigm - slots and workarea, menus arranged in a closed loop (circle, oval..), display of active menu item etc.