Once commercial promotion begins to fill the screen uninvited, the distinction between the Web and television fades. 

此处的形容词uninvited修饰的是the screen还是commercial promotion

以下为上下文：

Another major shift in the model for Internet commerce concerns the technology available for marketing.Until recently, Internet marketing activities have focused on strategies to "pull" customers into sites.In the past year, however, software companies have developed tools that allow companies to "push" information directly out to consumers, transmitting marketing messages directly to targeted customers.Most notably, the Pointcast Network uses a screen saver to deliver a continually updated stream of news and advertisements to subscribers' computer monitors.Subscribers can customize the information they want to receive and proceed directly to a company's Web site.Companies such as Virtual Vineyards are already starting to use similar technologies to push messages to customers about special sales, product offering, or other events.But push technology has earned the contempt of many Web users.Online culture thinks highly of the notion that the information flowing onto the screen comes there by specific request.Once commercial promotion begins to fill the screen uninvited, the distinction between the Web and television fades.That's a prospect that horrifies Net purists.