An application sends a ZGM_GETROWSPERPAGE to determine the number of rows that can be displayed in the ZeeGrid without vertical scrolling.
ZGM_GETROWSPERPAGE
wParam = 0; //not used; must be zero
lParam = 0; //not used; must be zero
The number of rows per display page. That is, the number of rows that can be displayed in the ZeeGrid without having to use the vertical scrollbar.