VC Set the dialog box background picture is not properly displayed radio control transparent

Create a dialog box item in VC2005, add a radio button, and then set the OnCtlColor dialog box in the background image as follows:

Ctestbrushdlgdlg::ctestbrushdlgdlg (cwnd* pparent/*=null*/)
: CDialog (Ctestbrushdlgdlg::idd, pparent)
{
M_hicon = AfxGetApp ()->loadicon (IDR_MAINFRAME);
M_nullbrush.createstockobject (Null_brush);
CBitmap Bitmap;
Bitmap. LoadBitmap (Idb_backup);
M_brush. CreatePatternBrush (&BITMAP);
}

Hbrush Ctestbrushdlgdlg::onctlcolor (cdc* PDC, cwnd* pwnd, UINT nCtlColor)
{
Hbrush HBR = Cdialog::onctlcolor (PDC, pwnd, nCtlColor);
Todo:change any attributes to the DC here

if (nCtlColor = = ctlcolor_static)
{
Pdc->setbkmode (Transparent);
return m_nullbrush;
}

Return (Hbrush) (m_brush.m_hobject);
}

1. When setting the project "Character set" to "use Unicode Character set", this radio background is the entire picture, not transparent.
2. When setting the project "Character set" to "use Multi-Byte Character set", the display is normal.