#620 – Why Are There So Many KeyPress Events?

When you press a single key within a WPF application, there are potentially a number of different keypress events that can fire.  But why are there so many different events that can possibly fire?

There are several reasons why there isn’t just a single keypress event.

  • Your application will only see the events for which you define a handler.  There is a large set of possible events so that you can choose which ones make sense for your application to handle.
  • Preview events exist so that a parent control can intercept keypress events for its children or descendants.  The tunneling allows you to decide at what level you want to preview the event.
  • The actual keypress event bubbles up the logical tree so that you can decide at what level to actually respond to the event.  In this way, you can handle multiple events in a single place.
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