Open file selection dialog programatically for hidden UploadItem

package com.client;

import com.shared.FieldVerifier;


public class FileUploadsmart implements EntryPoint {
    //FormPanel formPanel ;
    //TextField textField1;


 
  private final GreetingServiceAsync greetingService = GWT.create(GreetingService.class);
  VLayout layout;
 
  public void onModuleLoad() {
     
      RootPanel p=RootPanel.get();
    
      VLayout layout = new VLayout();
      layout.setSize("100px", "44px");
    
      final DynamicForm uploadForm = new DynamicForm();      
      uploadForm.setSize("54px", "147px");
      uploadForm.setEncoding(Encoding.MULTIPART);
    
    
     //  UploadItem fileItem = new UploadItem("image");
      
       HTML q =new HTML();
       q.setHTML("<"+"div style='display: block; width: 100px; height: 20px; overflow: hidden;'"+">"
      
                      +  "<"+"button style='width: 110px; height: 30px; position: relative; top: -5px; left: -5px;'"+">"+ "<a href=  'javascript: void(0)'>upload file</a>"+"</button>"
              
              +"<"+"input type='file' id='upload_input' name='upload' style='font-size: 50px; width: 120px; opacity: 0; filter:alpha(opacity: 0); position: relative; top: -40px; left: -20px'"+"/>" +
              
              "</div>" );
     
     
     
     
      uploadForm.setAction(GWT.getModuleBaseURL()+"upload");
   
      IButton uploadButton = new IButton("Attachment");
      uploadButton.addClickHandler(new com.smartgwt.client.widgets.events.ClickHandler()
      {
          @Override
          public void onClick(
                  com.smartgwt.client.widgets.events.ClickEvent event) {
              // TODO Auto-generated method stub
           
              
              uploadForm.submitForm();
          }
      });
      uploadForm.addChild(q);  
  ///uploadForm.setItems(fileItem);

      layout.setMembers(uploadForm, uploadButton);

    
    
    
      RootPanel.get().add(layout, 2, 2);

      
      

       
       
    }
}