Two ideas:

1) The SkinBase class creates a new WeakChangeListener every time, but it seems likely that only one is necessary. This won't have a huge impact, but it is likely to save a bit of memory and CPU.
2) Extract out all property change handling code into a separate class, so that it is only instantiated when required, and usable by classes other than SkinBase subclasses (for example TableColumnHeader which I have just improved with RT-24107).