An application sends a ZGM_APPENDROW to append a new row at the bottom of the grid. To add a new row at a position other than at the bottom of the grid, use ZGM_INSERTROW.
ZGM_APPENDROW
wParam = 0; //not used; must be zero
lParam = 0; //not used; must be zero
The cell index of the first cell (column 1) in the newly appended row.