def checksyntax(self, filename):
        self.shell = shell = self.flist.open_shell()
        saved_stream = shell.get_warning_stream()
        shell.set_warning_stream(shell.stderr)
        f = open(filename, 'r')
        source = f.read()
        f.close()
        if '\r' in source:
            source = re.sub(r"\r\n", "\n", source)
            source = re.sub(r"\r", "\n", source)
        if source and source[-1] != '\n':
            source = source + '\n'
        text = self.editwin.text
        text.tag_remove("ERROR", "1.0", "end")
        try:
            try:
                # If successful, return the compiled code
                return compile(source, filename, "exec")
            except (SyntaxError, OverflowError), err:
                try:
                    msg, (errorfilename, lineno, offset, line) = err
                    if not errorfilename:
                        err.args = msg, (filename, lineno, offset, line)
                        err.filename = filename
                    self.colorize_syntax_error(msg, lineno, offset)
                except:
                    msg = "*** " + str(err)
                self.errorbox("Syntax error",
                              "There's an error in your program:\n" + msg)
                return False
        finally:
            shell.set_warning_stream(saved_stream)