scrollbar does not work as required.

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C

Win32

Hi Seniors,
i have successfully implemented enabling vertical scroll bar during the run time based on user input. It does scroll down but i dont see the page scrolling down when the vertical bar is scrolling. Any suggestions. Trying since long time to fix this situation.

LRESULT CALLBACK WndProc( HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam )
{
	static int	cxCharWidth, cyCharHeight, cxClient, cyClient;
	static int	ChrCnt, iVertPos;
	int			i;
	HDC			hdc;
	PAINTSTRUCT ps;
	TEXTMETRIC	tm;
	static PMSG pmsg;
	SCROLLINFO	si;
	RECT		rect;
	// temp string //
	TCHAR	szTmp[50];
	// //
	
	switch( message )
	{
		case WM_CREATE:
			// get char width and height //
			hdc = GetDC( hwnd );
			GetTextMetrics( hdc, &tm );
			cxCharWidth  = tm.tmAveCharWidth;
			cyCharHeight = tm.tmHeight;
			ReleaseDC( hwnd, hdc );
			if( pmsg )
				free( pmsg );
			pmsg = malloc( 1000 * sizeof( MSG ) );
			break;

		case WM_SIZE:
			// get the screen size //
			cxClient = LOWORD( lParam );
			cyClient = HIWORD( lParam );
			break;

		case WM_CHAR:
			pmsg[ChrCnt++].wParam = wParam;
			InvalidateRect(hwnd, NULL, TRUE );
			break;

		case WM_PAINT:
			hdc = BeginPaint( hwnd, &ps );
			for( i = 0; i < ChrCnt; i++ )
			{
				wsprintf( szTmp, TEXT("Key pressed %c, times pressed: %2d"), pmsg[i].wParam, i );
				TextOut( hdc, 0, cyCharHeight * i, szTmp, lstrlen( szTmp ) );
			}
			// set vertical scroll bar position //
			si.cbSize = sizeof( si );
			si.fMask  = SIF_POS | SIF_RANGE | SIF_PAGE;
			si.nMin   = 0;
			si.nMax   = ChrCnt - 1;
			si.nPage  = cyClient / cyCharHeight;
			SetScrollInfo( hwnd, SB_VERT, &si, TRUE );
			// //
			EndPaint( hwnd, &ps );
			break;

		case WM_DESTROY:
			PostQuitMessage(0);
			break;
	}
	return DefWindowProc( hwnd, message, wParam, lParam );
}