OnCtlColor改变对话框背景色没有成功,怎么回事呀?

[altstop]

首先为CAaaDialog增加成员变量:
HBRUSH m_hRedBrush;

增加消息控制函数:
HBRUSH CAaaDialog::OnCtlColor(CDC* pDC, CWnd* pWnd, UINT nCtlColor)
{
HBRUSH hbr = CDialog::OnCtlColor(pDC, pWnd, nCtlColor);

// TODO: Change any attributes of the DC here


// TODO: Return a different brush if the default is not desired
if(nCtlColor==CTLCOLOR_DLG)
{
pDC->SetBkColor(RGB(255,0,0));
return m_hRedBrush;

}
return hbr;
}

[vcmute]

m_hRedBrush = CreateSolidBrush(RGB(255,0,0));

[altstop]

有点晕了,有SetBkColor(RGB(255,0,0)); 为什么还要::CreateSolidBrush(RGB(255,0,0));?
我用::CreateSolidBrush()可以改变颜色,但SetBkColor()不行
比如这样可以改变颜色:
if(nCtlColor==CTLCOLOR_DLG)
{

m_hRedBrush=::CreateSolidBrush(RGB(255,0,0));
return m_hRedBrush;
}

[菜牛]

pDC->SetBkColor(RGB(255,0,0));
这是设置字符背景，此后用TextOut()输出的字符具有红色背景，但是和对话框整个背景无关。