var ctrlman = m_Map.GetCtrlMan();
var uiman = ctrlman.GetUIMan();
uiman.SetMessage("MessageBox Test", 50000);

var stext = uiman.GetMessageBox();
if (stext) {
  alert(stext.GetCaption());
}

#include "CXCtrlMan.h"
#include "CXUIMan.h"
#include "CXUIStaticText.h"

CXCtrlMan ctrlman = m_Map.GetCtrlMan();
CXUIMan uiman = ctrlman.GetUIMan();
uiman.SetMessage(_T("MessageBox Test"), 50000);

CXUIStaticText stext = uiman.GetMessageBox();
if (stext.m_lpDispatch) {
  CString msg = stext.GetCaption();
  OutputDebugString(msg);
}