In general, .NET framework class provides the control to change the property. As an example, Label control's text can be modified using Text property.
Label1.Text = "...";
.NET provides the appropriate event to handle it. In this example, when the user changes the text content of Label, it will trigger a control and its delegate is:
public void Label1.OnTextChanged(object sender, RoutedEventArgs e)
But, your code uses the custom controls from stimulsoft. Mostly, it will support .NET framework base property and methods. For any particular control/property, you can check with them.