the properties Day, Month, etc. don't store any values in memory. As such they are not updated. Instead the properties implement the OnGet methods. They implement code to 'return' the correct value according to the selection made in the scroll list. For example, the OnGetHour method in Time Picker implementes following code:
Each time your application queries the value of the property Hour, the code is execututed returning the value coresponding to the scroll list position.
Does it help you further?