ShellExec Function

I was wondering if anybody could tell me the name of the refernce to the current file that is open in an MDI document.

I need to pass the current file in the window through the SHellExecute function to my browser and I have looked for it

with no luck. I built it using the MFC APPWizard so if anybody knows please help me. Here is the code I used

void CMainFrame::OnPreviewBrowser()

{

// Run the browser with a file

if (m_Dlg.m_Path != "")

{

ShellExecute(name of active file????,"open",m_Dlg.m_Path, NULL, NULL, SW_SHOW);

}

}