[Lazarus] TControlScrollBar implementation is weird

[Hans-Peter Diettrich]

This class contains some strange methods, which are not required or are 
Delphi incompatible.

SetAutoScroll always disables AutoScroll, no chance to enable it again. 
What's the purpose of that Lazarus-added method?

SetSize is not implemented (throws an exception). It would be simpler to 
make Size read-only, so that the compiler detects invalid calls. At 
least I'm missing a ToDo note.

DoDi