unfortunately this is not possible easily, as the non visible parts of
the window are not rendered on the screen, and therefore the Print()
method of the window cannot copy them.
If you need that really, you have to get the controls manually from the
window using the Windows API, retrieve their coordinates and fonts and
render them on the print surface.
I don't know if some advanced screenshot tools can accompish that
scrolling the subdatawindow on purpose.
Your best bet would be to enlarge the main window as possible to show
the entire subdata window.