qooxdoo provides complete support for event-based programming. If you have already programmed in QT or Java Swing, you'll find qooxdoo very similar. qooxdoo separates out the view widgets, model classes, and the controllers. Listeners observe the widget all the time and fire the right event based on the action. The action could be a click, a key entry, a selection of an item, mouse over the widget, change of the value in a table cell, and so on. An example of event-based programming is shown in the following diagram:
For example, you can add a listener for the Button widget to perform something on the click of a button. You can even set a command, which will be called on the execute action of the button-click event. qooxdoo provides lots of events for various widgets. For example, the List widget has many events such as changeSelection, addItem, removeItem, and so on.