C / C++ / MFC

So - it blocks untill it gets connection - after that it's ok. The question here is how to fix that block?

Use a separate thread for your socket communications if you need to respond to UI events while waiting for connections

struct MYSTRUCT
{
    int nMyInt;
    double dMyDouble;
    CString sMyString;

    CString GetDataString(CString sVarName)
    {
        CString sData;
        sData.Format("Contents of %s\n"
                     "   nMyInt = %d\n"
                     "   dMyDouble = %lf\n"
                     "   sMyString = %s", 
                     sVarName, nMyInt, dMyDouble, sMyString);
        return sData;
    };
};

struct MYSTRUCT
{
    int nMyInt;
    double dMyDouble;
    CString sMyString;

    CString sDataString;

    void SetDataString(CString sVarName)
    {
        sDataString.Format("Contents of %s\n"
                           "   nMyInt = %d\n"
                           "   dMyDouble = %lf\n"
                           "   sMyString = %s", 
                           sVarName, nMyInt, dMyDouble, sMyString);
    };
};

const int UWM_FOUNDHWNDADMIN = WM_APP + 1;

class CDlg : public CDialog
{
	//{{AFX_MSG(CD2LauncherDlg)
	//}}AFX_MSG
	afx_msg LRESULT OnFoundHwnd(WPARAM wParam, LPARAM lParam);
	DECLARE_MESSAGE_MAP()

private:
	PROCESS_INFORMATION* m_pProcessInfo;
	HWND                 m_hwnd;

	void RunComponent();
	void GetAppHWnd();
};

static BOOL CALLBACK EnumWindowsProcGetHwnd(HWND hwnd, LPARAM lParam);

void CDlg::RunD2RemoteAdmin()
{
	CString sFileName = GetProgramPath();
	AddBackSlash(sFileName);
	sFileName += "MyProgram.exe";

	if (FileExists(sFileName))
	{
		char cmdLine[1024];
		strcpy(cmdLine,(const char*)sFileName);

		m_pProcessInfo = new PROCESS_INFORMATION;
		if (!m_pProcessInfo)
		{
			CString sMsg;
			sMsg = "Could not allocate memory for component process info (not critical)";
			AfxMessageBox(sMsg);
			return;
		}

		STARTUPINFO StartupInfo = {0};
		StartupInfo.cb          = sizeof(STARTUPINFO);

		if (::CreateProcess(NULL, cmdLine, NULL, NULL, FALSE,
							0, NULL, NULL, &StartupInfo, m_pProcessInfo))
		{
			WaitForInputIdle(m_pProcessInfo->hProcess, 15000);
			GetAppHWnd();
		}		
	}
	else
	{
		CString sMsg;
		sMsg = "Could not find executable component";
		AfxMessageBox(sMsg);
	}
}

void CDlg::GetAppHWnd()
{
	DWORD  pid = m_pProcessInfo->dwProcessId;
	HANDLE ps  = OpenProcess(SYNCHRONIZE|PROCESS_TERMINATE, FALSE, pid);
	EnumWindows(EnumWindowsProcGetHwnd, pid);
	CloseHandle(ps);
}

LRESULT CDlg::OnFoundHwnd(WPARAM wParam, LPARAM lParam)
{
	wParam;
	lParam;

	m_hwnd = (HWND)wParam;
	DWORD dwPID = (DWORD)lParam;
	if (dwPID == m_pProcessInfo->dwProcessId)
	{
		// success
	}
	else
	{
		// failure
	}
	return 1L;
}

BOOL CALLBACK EnumWindowsProcGetHwnd(HWND hwnd, LPARAM lParam)
{
	CString sTitle;
	CWnd::FromHandle(hwnd)->GetWindowText(sTitle);

	DWORD wndPid;
	::GetWindowThreadProcessId(hwnd, &wndPid);
	if (wndPid == (DWORD)lParam && !sTitle.IsEmpty())
	{
		// You only have to do this if you know a portion of the window 
		// title of the program in question
		if (sTitle.Find("Remote Admin Monitor") >= 0)
		{
			theApp.m_pMainWnd->SendMessage(UWM_FOUNDHWNDADMIN, (WPARAM)hwnd, lParam);
		}
		return FALSE;
	}
	else
	{
		return TRUE;
	}
}