Method of IApplication
Opens an existing file with or w/o file dialog and returns reference to it
var ppDocument = Application.OpenFile(strPath, bInteractive, Syntax, nEncoding);
ppDocument = Application.OpenFile strPath, bInteractive, Syntax, nEncoding
CComPtr<ITextDocument> pDocument; HRESULT hr = Application.OpenFile(strPath, bInteractive, Syntax, nEncoding, &pDocument);