开发环境：VC6， a dialog based MFC application.

主界面：

为对话框添加WM_CTLCOLOR消息响应函数：

HBRUSH CDDlg::OnCtlColor(CDC* pDC, CWnd* pWnd, UINT nCtlColor) 
{HBRUSH hbr = CDialog::OnCtlColor(pDC, pWnd, nCtlColor);  if (pWnd->GetDlgCtrlID() == IDC_EDIT1)			// 获取子窗口控件ID{//pDC->SetTextColor(RGB(255, 0, 0));		// 设置文字颜色::SendMessage(GetDlgItem(IDC_EDIT1)->GetSafeHwnd(), WM_KILLFOCUS, 0, 0);	// 让其失去焦点，防止文字被选中//((CEdit*)pWnd)->SetSel(-1, 0);			// 不选中任何内容，与上句效果相同pDC->SetBkMode(TRANSPARENT);				// 设置背景透明return (HBRUSH)::GetStockObject(NULL_BRUSH);}return hbr;
}

运行效果：

看到了吧，打红圈的地方背景和文字颜色都透明了。

对话框加载背景图片的代码如下(为对话框添加WM_PAINT消息响应函数)：

void CDDlg::OnPaint() 
{if (IsIconic()){CPaintDC dc(this); // device context for paintingSendMessage(WM_ICONERASEBKGND, (WPARAM) dc.GetSafeHdc(), 0);// Center icon in client rectangleint cxIcon = GetSystemMetrics(SM_CXICON);int cyIcon = GetSystemMetrics(SM_CYICON);CRect rect;GetClientRect(&rect);int x = (rect.Width() - cxIcon + 1) / 2;int y = (rect.Height() - cyIcon + 1) / 2;// Draw the icondc.DrawIcon(x, y, m_hIcon);}else{//CDialog::OnPaint();        //要禁止这个调用CPaintDC dc(this);// 用于绘制的设备上下文CBitmap bmp;if(bmp.LoadBitmap(IDB_BITMAP1) == FALSE)return;BITMAP bmpStruct;bmp.GetBitmap(&bmpStruct);			// 为了获得图片大小CDC dcMemory;dcMemory.CreateCompatibleDC(&dc);	//创建内存DCCBitmap *pOldBmp = dcMemory.SelectObject(&bmp);CRect rect;GetClientRect(rect);dc.StretchBlt(0, 0, rect.Width(), rect.Height(), &dcMemory, 0, 0, bmpStruct.bmWidth, bmpStruct.bmHeight, SRCCOPY);//dc.BitBlt(0, 0, rect.Width(), rect.Height(), &dcMemory, 0, 0, SRCCOPY);dcMemory.SelectObject(pOldBmp);}
}