The main issue is that Free Vision (and Turbo Vision) uses the original "object" types introduced in Turbo Pascal 5.5 instead of "class" types introduced in Delphi which make a lot of things easier (e.g. the "class" RTTI allows for enough reflection to implement automatic serialization of objects, but "object" types do not have that and Free/Turbo Vision require manual serialization with registration of the VMT pointer -accessed via a fixed offset in object pointers- as a means to distinguish at runtime between different types). Free Pascal adds a few of the niceties of "class" types to "object" types (like private/protected/public sections -TP objects are all public- and properties) but Free Vision doesn't use those as it implements the original Turbo Vision API.

[0] https://wiki.lazarus.freepascal.org/images/1/19/Userscreen.p...