Oftentimes a visual element displays the representation of some underlying data value. In this case, you usually want to ensure that the visual element stays up-to-date and changes when the underlying data value changes.
For example, consider a window that contains two elements—a
TextBox at the top and a
Slider control beneath it. You'd like to have the
TextBox represent the value of the
Slider such that when you move the
Slider back and forth, the value in the
TextBox changes to show the
Slider's current value. This is illustrated in Figure 8-1, which shows the window in three different states.
Figure 8.1. The ...