creating a custom Editor for a Category (bundle of dependency Properties) is not working

[belmasnaoui]

trying to make a designer experience for a bundle of Properties is not working.
See : builder.AddCustomAttributes("CustomControlLibrary1.WpfCore.MyTextBox",CategoryEditor.CreateEditorAttribute(new MyCategoryEditor()));
The Idea is sample. In MyTextBox, I do have 2 or more properties which depend on each other. For instance: The MyTextBox displays a decimal number with floating point and an unit (millimeter, bar. etc.). Every unit will have a predefined count of digits after the decimal point.
Changing the unit affects the count of digits after the decimal point.
Is creating a category for some type is not supported any longer?

Best regards