So far, their position inside the container was determined when
initializing the interface. However, if a child were resized
afterwards, the container would not adjust its elements accordingly.
Moreover, the implementation for gui_container relied on hacking the
children's X/Y coordinates, which could only be done once.
Now, two additional members have been added to gui_common so that
specific X/Y offset can be determined by the parent, additionally to the
traditional rules followed by gui_coords. Despite the extra memory
footprint, it now allows containers to set specific X/Y offsets for
their children on every game cycle.
Xavier Del Campo Romero