title: Disable of date in DatePicker doen't works
body: <p>I am trying to disable all the date in the <code>DatePicker</code> GWT component, here is my sample of code :</p>
  
  <pre><code>datePicker.addShowRangeHandler(new ShowRangeHandler&lt;Date&gt;() {
  
      public void onShowRange(ShowRangeEvent&lt;Date&gt; event) {  
       System.out.println("First date : " + event.getStart());
       System.out.println("Last date : " + event.getEnd());
  
       System.out.println("First date from date picker : " + datePicker.getFirstDate());
       System.out.println("Last date from date picker : " +   datePicker.getLastDate());
  
        // Disable all the date shown by the Calendar
       List&lt;Date&gt; dateList = new ArrayList&lt;Date&gt;(); 
       Date currentDate = event.getStart();
  
      while(!currentDate.after(datePicker.getLastDate())) {
         Date updateDate = CalendarUtil.copyDate(currentDate);
         dateList.add(updateDate);
         CalendarUtil.addDaysToDate(currentDate, 1);
      }
  
      for(Date date : dateList) {
        System.out.println("Date selected : " + date);
        System.out.println("date visibility : " + datePicker.isDateVisible(date));
     }
    }
  
  
  });
  </code></pre>
  
  <p>Date visibility is always false , it keep telling me that all the date are not visible, but it should be true since it' between the first date and last date, anybody know a way to disable date in calendar?, so if tried the method <code>setTransientOnEnables()</code> on the datePicker for any of the date I keep getting an exception as the date arenot visible.</p>
  
  <p>I had tried also impleenting my own <code>DefaultClendarView</code> but it requires protected class which is not available by GWT.</p>