Adds an action to the action group.
If the action group already contains an action with the same name as @action then the old action is dropped from the group.
The action group takes its own reference on @action.
a #GAction
Deprecated: Use g_action_map_add_action()
2.28
See Implementation
Adds an action to the action group.
If the action group already contains an action with the same name as @action then the old action is dropped from the group.
The action group takes its own reference on @action.