1. In an online presentation environment having a presenter transmitting screen data to a viewer over a network, a method of providing to the presenter visual feedback regarding the screen data received by the viewer comprising: (a) transmitting data representing changed visual data; (b) receiving confirmation of receipt of the changed visual data from the viewer; (c) generating a representation of the visual data received by the viewer responsive to the received confirmation data; and (d) displaying the generated representation at the presenter.