XGL components are independent of legacy GWT widgets and events
GWT Steering Committee announced that in GWT 3.0, the current widget system would not be supported, and this is why we started XGL in the first place.
With XGL no worries, your project will continue to compile and work in the future. Our component hierarchy has no link with the old GWT widgets. Moreover, XGL has an event system independent of the GWT events.
Independence is an invaluable asset for XGL. We can be more creative and add functionalities that are unavailable in GWT. For example, you can attach XGL events to any phase of the browser event cycle (GWT supports only the "Bubble" phase). Furthermore, Presto, an XGL component, manages and schedules all the reads and writes to the DOM (Document Object Model). Presto prevents a typical issue in large web applications: layout trashing or reflows.