bug: ComboBox association Attribute written as pointer; DESCRIBE shows CaptionAttribute #21
Description
When creating a ComboBox with an association datasource, the Attribute property is serialized as an association pointer instead of an attribute reference. DESCRIBE reads back CaptionAttribute rather than the original field name.
Repro: CREATE PAGE with COMBOBOX ATTRIBUTE $this/AssignedTo SOURCE DATABASE ... CAPTION ATTRIBUTE $this/Name
Impact: ComboBox association datasource widgets cannot be roundtripped. Affects 17-custom-widget-examples.mdl.
Severity: HIGH — widget property data loss; widget behaviour changes on re-import.
Discovered via: Automated roundtrip test (2026-03-25)