怎么动态的改变static控件的背景颜色

//class CxxxDlg里增加HBRUSH m_brush;
//BOOL CxxxDlg::OnInitDialog()加入m_brush = NULL;
//把static的ID改为IDC_MYSTATIC

HBRUSH CxxxDlg::OnCtlColor(CDC* pDC, CWnd* pWnd, UINT nCtlColor)
  {
      HBRUSH hbr = CDialog::OnCtlColor(pDC, pWnd, nCtlColor);
 
     if (pWnd->GetDlgCtrlID() == IDC_MYSTATIC && m_brush != NULL)
     {
        hbr = m_brush;
     }
  
     return hbr;
  }

void CxxxDlg::OnBnClickedButton1()
  {
      if (m_brush)
        DeleteObject(m_brush);
        
     m_brush = CreateSolidBrush(RGB(255, 0, 0)); // 根据需要设置
     
     Invalidate();  // GetDlgItem(IDC_MYSTATIC)->Invalidate();
  }