@Override
protected void fillPopupBarDescriptors() {
 super.fillPopupBarDescriptors();

 AbstractPopupBarTool tool = null;

 ImageDescriptor imageDescriptor = null;
 Image image = null;

 tool = new XXXPopupBarTool(getHost(), null);
	
 imageDescriptor = Activator.imageDescriptorFromPlugin(Activator.PLUGIN_ID, "/icons/tool.gif");
 image = imageDescriptor.createImage();
			
 addPopupBarDescriptor(null, image, tool, "ToolTip");
}			

public XXXPopupBarTool(EditPart epHost, CreateRequest theRequest) {
 super(epHost, theRequest);
}

@Override
protected Request createTargetRequest() {
 return new RequestForThisTool();
}

@Override
protected Command getCommand() {
 return new CommandForThisTool();
}

/**
* @generated
*/
protected void createDefaultEditPolicies() {

 //Generated code before...


  removeEditPolicy(EditPolicyRoles.POPUPBAR_ROLE);
  installEditPolicy(EditPolicyRoles.POPUPBAR_ROLE, new YourPopupBarEditPolicy());
}

imageDescriptor = Activator.imageDescriptorFromPlugin(Activator.PLUGIN_ID, "/icons/tool.gif");

imageDescriptor = AbstractUIPlugin.imageDescriptorFromPlugin(Activator.PI_APP, "open.gif");

public IntrospectPopupBarTool(EditPart epHost, CreateRequest theRequest) {
 super(epHost, theRequest);
}

@Override
protected Request createTargetRequest() {
 ChangePropertyValueRequest req = new ChangePropertyValueRequest("XXXX", "XXX");
 return req;
}

@Override
protected Command getCommand() {
 return new XXXCommand((IGraphicalEditPart)getHost());
}

private IGraphicalEditPart host = null;
	
/**
 * 
 * @param host Element to introspect
 */
public IntrospectCommand(IGraphicalEditPart host){
 this.host = host;
}

@Override
public void execute() {
 super.execute();
		
 Shell shell = PlatformUI.getWorkbench().getActiveWorkbenchWindow().getShell();
 MessageBox m = new MessageBox(shell);
 m.setMessage("Hello World");
 m.open();
}

List types = Collections.singletonList(ActivityElementTypes.Action_2001);
CreateUnspecifiedTypeRequest gefRequest = new CreateUnspecifiedTypeRequest(types, PreferencesHint.USE_DEFAULTS);
gefRequest.setLocation(...);
gefRequest.setSize(...);
EditPart containerEP = .... //find EP that should host the new element, DiagramEditPart for top-level elements.
Command gefCommand = containerEP.getCommand(gefRequest);
if (gefCommand.canExecute()) {
   //execute 
}