I wouldn't call it universal, standard UI gadgets such as edit boxes *don't* do this by default, nor do I see anyway, without custom code, to make them do this.
In other words its not Windows doing this, but each application.
Maybe the "rich text control" in Windows has built in word selection? I know "Wordpad" is based off that Windows control, and it can turn that word-selection behavior on and off? Anyone?