问题
Is there a simple way to add handlers/listeners to widgets so that the change to visibility can be detected ? Or do i have to create a system of my own ? (which means creating other widgets that wrap needed widgets and trigger events when setVisible(...) is called)
回答1:
Standard widgets have their own listeners and handlers. If your application requires your own events then you have to define custom user defined events, listener and handlers.
回答2:
overite setVisible(boolean visible) extend UIObject or use deffered binding
来源：https://stackoverflow.com/questions/10396983/gwt-adding-visibility-true-false-handler