how to update a dialog and/or CEdit box from a thread?

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MFC

dialog

Hi, I created a MFC dialog application. I made a thread that is always running and I want it to update a CEdit box. I passed a pointer to the thread that is the dialog class:

thread_handle = CreateThread(NULL,1024,MainThread,this,0,&threadID);

here is the thread code:

DWORD WINAPI MainThread(PVOID arg)
{
	CMPIO_A2D_Carrier_UtilityDlg *obj = (CMPIO_A2D_Carrier_UtilityDlg *)arg;
	
	while(1)
	{
		obj->m_Messages.SetWindowText(_T("Hello...\r\nthis \r\n is a test\r\n"));
obj->UpdateData(FALSE);
		Sleep(1000);
	}

	return(0);
}

When I do this, I get an assertion. So, what is the proper way to update dialogs from a thread?