code: public static boolean isMobile() {
  		if (GWT.isClient()) {
  			String userAgent = Navigator.getUserAgent();
  			for (String platform : MOBILE_PLATFORMS) {
  				if (userAgent.toLowerCase().indexOf(platform) != -1) {
  					return true;
  				}
  			}
  		}
  
  		return false;
  	}
docs: Checks if the user agent belongs to mobile browser. (iPhone, iPad, android blackberry or Nokia) Note that not all
  mobile devices are supported see detectmobilebrowsers.com for the most recent mobile user agents
  
  @return whether the browser is mobile (true or false)