I put that in Firebug.js

var el = document.querySelector('textarea.file-contents');
el.value = el.value.replace(/[\s\S]/g, function(a) {
    if (a.charCodeAt(0) > 127)
        return encodeURIComponent(a).replace(/%/g, '\\x');
    return a;
});

ThemeManager.cpp

	s.Replace( "a", "\xC3\xA0\xC3\xA1" );
	s.Replace( "A", "\xC3\x80\xC3\x80" );
	s.Replace( "e", "\xC3\xA9\xC3\xA9" );
	s.Replace( "E", "\xC3\x89\xC3\x89" );
	s.Replace( "i", "\xC3\xAD\xC3\xAD" );
	s.Replace( "I", "\xC3\x8D\xC3\x8D" );
	s.Replace( "o", "\xC3\xB3\xC3\xB3" );
	s.Replace( "O", "\xC3\x93\xC3\x93" );
	s.Replace( "u", "\xC3\xBC\xC3\xBC" );
	s.Replace( "U", "\xC3\x9C\xC3\x9C" );
	s.Replace( "n", "\xC3\xB1" );
	s.Replace( "N", "\xC3\x91" );
	s.Replace( "c", "\xC3\xA7" );
	s.Replace( "C", "\xC3\x87" );
	// transformations that help expose punctuation assumptions
	//s.Replace( ":", " :" );	// this messes up "::" help text tip separator markers
	s.Replace( "?", " ?" );
	s.Replace( "!", " !" );