TypeConverter  and TypeConverter Attribute. In plain language, if one of your properties is not a simple data type, you'll need a type converter. adxSuperPanel uses a number of properties (Shadow, Corners, Borders and others) that require conversion. If a property is a class, which in turn contains other properties at minimum you must code:

 <TypeConverter(GetType(ExpandableObjectConverter))>

The Help says that ExpandableObjectConverter provides a type converter to convert expandable objects to and from various other representations, in plain language, using the .NET class ExpandableObjectConverter will cause the property to display the +/- on the property grid. adxSuperPanel has one class , GradientTypeConverter inheriting from ExpandableObjectConverter .

ToString Function Every .NET class inherits the ToString Function from the Object class. adxSuperPanel  uses the ToString function to return some useful information about the class. Otherwise the function might return a default  string we may not like.

DesignerSerializationVisibility  Attribute This attribute determines how the system will serialize a property.

UITypeEditor  is a design time class that will help you to edit property values. adxSuperPanel makes an extensive use of a slider type editor, using the track control to enter data.

Lookup the classes: TrackbarBase, UITypeEditTrackHandler and TrackHandlerEditor.

Another UITypeEditor is the GradientFillEditor. adxSuperPanel uses this class to paint the value's thumbnail.