RoutedEventArgs.Source vs Sender

Question

What is the difference between sender and source in wpf event handling?

For example, say I had an ellipse in a canvas, and clicked on the ellipse:

Answer 1

Bubbles!

The sender is the object that the event is being raised from, whereas source was the original element that is causing the event to be raised.

Like in this case:

private void tc1_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
}

In this case, if you change the SelectedItem on the Sub-TabControl, sender will equal tc1, Source will equal tc2.