/**
* A helper function for derived classes, for assignment of strings.
*
* This 'normalizes' newString, and then if it is different from oldString,
* it invalidates the DOM, frees the old string, and returns the new.
* If not different, it frees the new string and just returns the old value.
/**
* A helper function for derived classes, for assignment of strings.
*
* This 'normalizes' newString, and then if it is different from oldString,
* it invalidates the DOM, frees the old string, and returns the new.
* If not different, it frees the new string and just returns the old value.