ClistCtrl : merge Bitmaps from ImageList to change item height

Hi,

I am trying to modify dynamically image list associated with a
CListCtrl. My first question is :

1) When changing an image list with another one with biggest image does
it automatically resize item height of my CListCtrl ?

2) How can I create an new imagelist from an already attached imagelist
and merge the existing image inside a white(or even better transparent
color). The main idea is to be able to specify item height.
I have tested all tricks used on code project and code guru and it works
but it seems there some issues whith scrollbar in my case.
I have played with Scrollinfo but control doesn't seem to like it.

The other method is to change font size but I am not really statisfied
with this method because I don't want to change the specified font.
So my last attempt is to create(if it doesn't exist) or modify an
imagelist and specify bigger icons.

I wrote the following code with no success

// Create a white bmp
HBITMAP CxListCtrl::CreateBitmap(int nHeight, COLORREF crfColor)
{
    HBITMAP hOutBmp = NULL;
    BITMAP bm = {0};
    HDC hMemDc = CreateCompatibleDC(NULL);
    HBITMAP hBmp= CreateCompatibleBitmap(hMemDc, nHeight, nHeight);
    SelectObject(hMemDc, hBmp);
    HBRUSH hBkBrush = CreateSolidBrush( crfColor );
    RECT rcBkGnd = {0, 0, nHeight, nHeight};
    HBRUSH hOldBrush= (HBRUSH)SelectObject(hMemDc, hBkBrush);
    FillRect(hMemDc, &rcBkGnd, hBkBrush);
    SelectObject(hMemDc, hOldBrush);
    DeleteObject(hBkBrush);

    hOutBmp = hBmp;
    DeleteDC(hMemDc);

    return hOutBmp;
}

// Merge 2 bitmaps (the white one created from CreateBitmap and the
other from exiting imagelist)
HBITMAP CxListCtrl::AddBitmaps(HBITMAP *pahBmps, DWORD cntFiles)
{
    HBITMAP hOutBmp = NULL;
    do
    {
        BITMAP bm = {0};
        HDC hMemDc = CreateCompatibleDC(NULL);
        HDC tempDc = CreateCompatibleDC(hMemDc);
        HBITMAP hMemOld = (HBITMAP)SelectObject(hMemDc, pahBmps[0]);

        HBITMAP hBmp= CreateCompatibleBitmap(hMemDc, m_nItemHeight,
m_nItemHeight);
        if (NULL == hBmp) break;

        SelectObject(hMemDc, hBmp);
        HBRUSH hBkBrush = CreateSolidBrush( RGB(255,255,255) );
        RECT rcBkGnd = {0, 0, m_nItemHeight, m_nItemHeight};
        HBRUSH hOldBrush= (HBRUSH)SelectObject(hMemDc, hBkBrush);
        FillRect(hMemDc, &rcBkGnd, hBkBrush);
        SelectObject(hMemDc, hOldBrush);
        DeleteObject(hBkBrush);

        DWORD ixBmp = 0;
        int nX = 0, nY = 0;
        int ixRow = 0, ixCol = 0, nPreRawY = 0;
        while(ixBmp < cntFiles)
        {
            GetObject(pahBmps[ixBmp], sizeof(BITMAP), &bm );
            HBITMAP hOld = (HBITMAP)SelectObject(tempDc, pahBmps[ixBmp]);
            BitBlt(hMemDc, nX, nY, bm.bmWidth, bm.bmHeight, tempDc, 0, 0, SRCCOPY);
            SelectObject(tempDc, hOld);
            //GetNextXY(nX, nY, bm, ixRow, ixCol, nPreRawY);
            ixBmp++;
        }
        SelectObject(hMemDc, hMemOld);
        hOutBmp = hBmp;
        DeleteDC(tempDc);
        DeleteDC(hMemDc);
    }while(0);

    return hOutBmp;
}

void CxListCtrl::SetItemHeight(int nItemHeight)
{

    CBitmap bmp;
    CImageList imgList;
    CImageList* pImgList = GetImageList( LVSIL_SMALL );
    if (pImgList == NULL)
    {

        /*if (m_nItemHeight > (imgInfo.rcImage.bottom - imgInfo.rcImage.top) )
        {

            imgList.Add( &bmp,(COLORREF)0x000000);
        }*/
    }
    else
    {
        int nImgCount = 0, nImgSize = 0;
        IMAGEINFO imgInfo;
        nImgCount = pImgList->GetImageCount();
        pImgList->GetImageInfo(0, &imgInfo);
        nImgSize = imgInfo.rcImage.bottom - imgInfo.rcImage.top;

        // Create a White BMP with the specified item height
        HBITMAP hMaskBmp = CreateBitmap( nItemHeight, RGB(255,255,255) );

        // Create a new imagelist and merge each image with white bmp
        imgList.Create(nItemHeight, nItemHeight, ILC_MASK | ILC_COLOR, 1, 1);
        for (int i = 0; i < nImgCount; i++)
        {
            pImgList->GetImageInfo(0, &imgInfo);

            //GetImageFromList(pImgList, i, &bmp);
            HBITMAP hBitmaps[2] = { hMaskBmp, imgInfo.hbmImage };
            //AddBitmaps(

        }

    }

    m_nItemHeight = nItemHeight;
}