(SOLVED) Showing partial area of plugin editor in TopLevelWindow

I have TopLevelWindow which contains hosted VST plugin editor. Editor is larger than window, so only part of it is visible. Now, sometimes i want to make other area of editor visible.

I don’t want to mess with ViewPort/plugin editor combo (i’ve read it it’s not possible at all - or is it??), so on windows, i am using Windows API function ScrollWindow, which does the job perfectly. Maybe it is not the best solution, but i couldn’t think of any better way to do it.

Now i must do the same on Mac OS. Any idea or hint how and where to start would be greatly appreciated (cocoa ??).

Thx!!!

Edit:

I am not sure where i got the info that Viewport can’t contain plugin editor. This is definitively wrong info, because i’ve just managed to do it - working on Windows and Mac OS.