BS_OWNERDRAW and GDI+ - winapi

Question

I'm trying to create a launcher window with 5 "invisible" buttons that have a smaller partially transparent image centered inside them. The image inside changes depending on whether the user is hovering over the button. In this example the images are resources IDB_Website1 and IDB_Website2.
The images are in .png format. I'm using GDI+ and loading PNG files from resources with http://www.codeproject.com/Articles/3537/Loading-JPG-PNG-resources-using-GDI.
I've used BS_OWNERDRAW to handle the graphics of the button. The problem is that I don't know how to link the "PNG from resources" code to the parent's WM_DRAWITEM. With the current way I've done the code, I lose the transparency of the .png by going through HBITMAP.
Global variable:
HBITMAP globalpic;
Main wndproc:
case WM_CREATE:
{
HWND hwndButton = CreateWindow(TEXT("button"), NULL,
WS_CHILD | WS_VISIBLE | BS_OWNERDRAW,
190, 230, 260, 50, // <- the larger rect size
hWnd, (HMENU) HT_BUTTON1, hInst, NULL);
HTButton = (WNDPROC) SetWindowLong(hwndButton, GWL_WNDPROC, (LONG) ButtonProc);
}
case WM_DRAWITEM:
{
DRAWITEMSTRUCT* lpDrawItem = (DRAWITEMSTRUCT*)lParam;
HBITMAP hBmp;
HDC hdc = CreateCompatibleDC(NULL);
if (hovering) // <- mousehover detection, not included
{
gdi.CreateBM(IDB_Website2, _T("PNG"), hInst, hdc, 62, 100, 200, 40);
} else {
gdi.CreateBM(IDB_Website1, _T("PNG"), hInst, hdc, 62, 100, 200, 40);
}
hBmp = globalpic; // get the global var gdi.CreateBM created
DeleteDC(hdc);
BITMAP bm;
GetObject(hBmp, sizeof(bm), &bm);
HDC hMemDC = CreateCompatibleDC(NULL);
HBITMAP hOldBmp = (HBITMAP)SelectObject(hMemDC, hBmp);
StretchBlt (lpDrawItem->hDC,
lpDrawItem->rcItem.left + 30,
lpDrawItem->rcItem.top + 5,
200, <- the width of image
40, <- the height of image
hMemDC,
0, 0,
bm.bmWidth,
bm.bmHeight,
SRCCOPY);
SelectObject(hMemDC, hOldBmp);
DeleteDC(hMemDC);
DeleteObject(hBmp);
break;
}
class GDI's method CreateBM.
Currently, since I don't know of a better way, it sends the HBITMAP to the global variable globalpic. The problem is that by doing this, I lose transparency.
void CreateBM(UINT menuid, LPCTSTR pType, HMODULE hInst, HDC hdc, int x, int y, int w, int h)
{
CGdiPlusBitmapResource m_pBitmap;
m_pBitmap.Load(menuid, pType, hInst);
m_pBitmap.m_pBitmap->GetHBITMAP(RGB(255, 255, 0), &globalpic);
//m_pBitmap.m_pBitmap->GetHBITMAP(GetBkColor(hdc), &globalpic); // <- no-go either
}
Any way I could do this more directly? I feel that going through the HBITMAP route is completely unnecessary but I couldn't for the life of me figure out how I should do it.
Then again, if using the HBITMAP way is fine, any pointers on how I could make the color (I guess (RGB(255, 255, 0) ...?) transparent with the current implementation?
Answering to Hans:
I also have a GDI method like this, but it's unused at the moment because I couldn't get the image removed after drawing it (as is needed when hovering changes the image):
void Create(UINT menuid, LPCTSTR pType, HMODULE hInst, HDC hdc, int x, int y, int w, int h)
{
Graphics grpx(hdc);
ht_img = new CGdiPlusBitmapResource();
ht_img -> Load(menuid, pType, hInst);
grpx.DrawImage(*ht_img, x, y, w, h);
delete ht_img;
}