object help please

im creating a little gui system

I have gadget types like:

type gui_element
field gadget_number
endtype

type button extends gui_element

endtype

type textbox extends gui_element

endtype

I want to gather the gadgets onto a window

so in my window class I have a list of gadgets that it contains

type window
field gadget_list:tlist

method add_gadget_to_window(o:object)
o.gadget_number=gadget_list.count()+1
endtype

endtype



but I cant access the field gadget_number from o:object
how do I do that?