John,
Thanks for the tip.
I played around with this and finally came up with:
void MainDlg_OnSize(HWND hwnd, UINT state, int cx, int cy)
{
RECT rcDlg, rcGrid;
GetClientRect(hwnd,&rcDlg);
GetClientRect(hList1,&rcGrid);
MapWindowPoints(hList1,hwnd,(LPPOINT)&rcGrid.left,2);
SetWindowPos(hList1,NULL,0, 0,rcDlg.right - rcGrid.left,
rcDlg.bottom - rcGrid.top,SWP_NOMOVE);
}