C / C++ / MFC

HWND hParent = FindWindow("AIM_IMessage", NULL);
if (hWnd != NULL) {
 // use something like this to find the child window
 HWND hChild = FindWindowEx(hParent, NULL, "ChildWindowClassName", NULL);
 if (hChild != NULL) {
   ::SetWindowText(hChild, "some text");
 }
} else {
  ::MessageBox(NULL, "Could not find IM window", "Error", MB_ICONINFORMATION);
}

CWnd *pMyWindow = FindWindow("AIM_IMessage", NULL);
pMyWindow->SetWindowText("Some Text");

pMyWindow->SendMessage(params)

pMyWindow->GetSafeHwnd();

void CMyDialogClass::SetTheFonts()
{
  m_fntBigFont.CreatePointFont(24, _T("Arial")); 
  // NOTE: This must be a member variable, if you create a local variable 
  // on the stack it will be destroyed, and the font won't be set correctly.

  m_fntLittleFont.CreatePointFont(6, _T("Arial"));

  m_edtBigEditControl.SetFont(&m_fntBigFont);
  m_edtLittleEditControl.SetFont(&m_fntLittleFont);
}

if(pWnd->GetDlgCtrlID()==IDC_EDIT1)
{
	pDC->SetBkColor(RGB(255,0,0));
	return CreateSolidBrush(RGB(255,0,0));
}

CMainFrame::OnPressMyButton()
{
  CMDIChildWnd *vpChildFrame = MDIGetActive();
  if (vpChildFrame != NULL)
  {
    CDocument *vpActiveDocument = vpChildFrame->GetActiveDocument();
    if (vpActiveDocument != NULL)
    {
      DoSomeStuffWith(vpActiveDocument); // Do your array stuff here.
    }
  }
}