title: List all the widgets of a page/panel in GWT
body: <p>Is there a programmatic way to read all the widget a GWT page or Panel contains? </p>
  
  <p>I have several error labels in my form, all suffixed by "ErrorLabel" and I'd like to find them and clear them. I can do a list of them, but I figured out I can actually automate that if I had some...</p>
  
  <p>I am using UiBinder.</p>