overrid model chang properti chang event mee model chang mee code review model facad messag owner model facad paramet mee sourc object par mee sourc updat argument paramet owner par mee mee sourc owner model facad action mee sourc model facad oper mee sourc model facad argument mee sourc model facad signal mee sourc updat listen owner need updat chang notat subsystem tfm str notat gener owner trim fig set text str updat arrow damag 