code: public JQMButton setLeftButton(String text, JQMPage page, DataIcon icon) {
          if (page == null)
              throw new RuntimeException("page cannot be null");
          return setLeftButton(text, "#" + page.getId(), icon);
      }
docs: Creates a new {@link JQMButton} with the given text and linking to the
  given {@link JQMPage} and with the given icon and then sets that button
  in the left slot. Any existing right button will be replaced.
  
  @param text
  the text for the button
  @param page
  the optional page for the button to link to, if null then
  this button does not navigate by default
  @param icon
  the icon to use or null if no icon is required
  
  @return the created button