In this section:
%gp (Window Postion) takes two integers as arguments. When the window is created these integers are set to the screen x, y co-ordinates of the point where the %gp (Window Postion) format is used. Typically these values are used to position other windows over appropriate parts of a main window by using the %sp (Window Position) format. It is also used for child windows. Each time the window is moved or re-sized the x, y pair is updated.
i=winio@('Press this button to conceal it! &')
INTEGER FUNCTION myfunc()
c--- Window will be positioned relative to the button
c--- control in the main window