code: public void open(String title, int width, int height) {
          assertSteps();
          if (window == null) {
              window = new DefaultWindow(title);
              window.setWidth(width);
              window.setHeight(height);
              window.trapWidget(asWidget());
              window.setGlassEnabled(true);
              window.addCloseHandler(closeEvent -> {
                  // calls the cancel() to remove the datasource as the user wants to cancel the ADD operation.
                  onCancel();
              });
          } else {
              window.setTitle(title);
          }
          resetContext();
          for (WizardStep<C, S> step : steps.values()) {
              step.reset(context);
          }
          state = initialState();
          pushState(state);
          window.center();
      }
docs: Same as {@link #open(String)} with the ability to pass a different width and height.