Add the specified handler to the set of functions to be called when this object receives focus events (in or out). If the handler is already added it is not added again
The AtkFocusHandler to be attached to component
a handler id which can be used in atk_component_remove_focus_handler or zero if the handler was already added.
See Implementation
Add the specified handler to the set of functions to be called when this object receives focus events (in or out). If the handler is already added it is not added again