- as example i create a script varaibale for Text2D and name it also Text2D
- now i extend this script Variable with Lua (or with Awakening ?) with a user defined property as example Text2D.myVariable
- this property .myVariable is now listed in the user interface
- i can animate this property like any other standard property like scale or transparence

Good idea, we'll consider this, thanks!
LUA is a flexible language, you can freely add property to existing script variable. For example, Text2D.note='my comments'.