Polymer PaperToast show() method not found?

Hi all,

I've hooked up the vaadin polymer widgets with my gwt project. I am using gwt "2.8.0-beta1". My vaadin gradle import is:

    com.vaadin.polymer:vaadin-gwt-polymer-elements:1.2.3.0

I can use some widgets just fine, such as PaperButton, PaperCard. I'm having trouble showing a PaperDialog or a PaperToast. For example:

PaperToast toast = new PaperToast();
toast.setText("hi");
toast.show();

It seems that the "show()" method cannot be found:

com_vaadin_polymer_paper_widget_PaperToast_$
  getPolymerElement__Lcom_vaadin_polymer_paper_widget_PaperToast_2
    Lcom_vaadin_polymer_paper_PaperToastElement_2(...).show is not a function

Same thing happens with PaperDialog and trying to call its "open()" method.

Does anyone have an idea what I'm doing wrong?

Thanks