Files in the lib/ folder should NOT be modified!
They may be replaced by an update of a library.
But sometimes it's necessary:

The following changes have been made:

# lib/php/dwoo/plugins/builtin/functions/truncate.php
Replaced substr() and strlen() with multibyte versions.
Added utf-8 as encoding. Supports now truncating of asian (japanese) characters.

# lib/js/prototype.js
Applied patch for regression in Form.serialize(true/false).
https://github.com/sstephenson/prototype/pull/66/files (see src/prototype/dom/form.js)