// sets the login textfield with "user", if is selected and user
// presses enter, it prints Login
var login : String = "username";
var login2 : String = "no action here";

function OnGUI () {
    GUI.SetNextControlName ("user");
    login = GUI.TextField (Rect (10,10,130,20), login);

    login2 = GUI.TextField (Rect (10,40,130,20), login2);
    if (Event.current.Equals (Event.KeyboardEvent ("return")) &&
    GUI.GetNameOfFocusedControl() == "user")
        Debug.Log ("Login");
    if (GUI.Button (new Rect (150,10,50,20), "Login"))
        Debug.Log ("Login");
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    public string login = "username";
    public string login2 = "no action here";
    void OnGUI() {
        GUI.SetNextControlName("user");
        login = GUI.TextField(new Rect(10, 10, 130, 20), login);
        login2 = GUI.TextField(new Rect(10, 40, 130, 20), login2);
        if (Event.current.Equals(Event.KeyboardEvent("return")) && GUI.GetNameOfFocusedControl() == "user")
            Debug.Log("Login");
        
        if (GUI.Button(new Rect(150, 10, 50, 20), "Login"))
            Debug.Log("Login");
        
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    public login as string = 'username'

    public login2 as string = 'no action here'

    def OnGUI():
        GUI.SetNextControlName('user')
        login = GUI.TextField(Rect(10, 10, 130, 20), login)
        login2 = GUI.TextField(Rect(10, 40, 130, 20), login2)
        if Event.current.Equals(Event.KeyboardEvent('return')) and (GUI.GetNameOfFocusedControl() == 'user'):
            Debug.Log('Login')
        if GUI.Button(Rect(150, 10, 50, 20), 'Login'):
            Debug.Log('Login')