

DesignerException: 103 (Unknown GUI toolkit). For example, the compilation unit uses SWT classes, but the SWT/JFace libraries are not included into the classpath. WindowBuilder does not understand this GUI type/pattern in a supported GUI toolkit. WindowBuilder does not recognize the GUI toolkit or library used in this class. This class is not an editable UI class and contains no UI components.

This can be caused by one of the following reasons:

The parser parsed the compilation unit, but can't identify any GUI toolkit, so WindowBuilder can't display any GUI to edit.
