Question

In my GWT application, I want to ask a user confirmation when he navigates out of the current application, i.e. by entering a URL or closing the browser. This is typically done by registering a ClosingHandler and setting the desired dialog message in the onWindowClosing method. This seems to work well.

However, if the user tries to navigate say to http://www.gmail.com (by typing it in the URL bar) and hits Cancel to indicate he doesn’t want to navigate, then my app keeps running but the browser’s URL bar keeps indicating http://www.gmail.com. This causes a number of problems later in my application and will give the wrong result if the user bookmarks the page.

Is there a way to automatically reset the URL when the user presses Cancel?

Or, alternatively, is there a way to detect the user pressed the Cancel button? If so, is there a way to set the URL without triggering a ValueChangeEvent? (I could add some logic to prevent this, but I’d rather use a built-in mechanism if it exists.)

Answer 1

I managed to do this. It looks like GWT DeferredCommand are executed after the confirmation window has been closed. This, combined with Hilbrand’s answer above, give me exactly what I want. Here is exactly what I do:

  public final void onWindowClosing(Window.ClosingEvent event) {
    event.setMessage(onLeaveQuestion);
    DeferredCommand.addCommand( new Command() {
      public void execute() {
        Window.Location.replace(currentLocation);
      }
    });
  }

Where currentLocation is obtained by calling Window.Location.getHref() every time the history token changes.