Hi in my application I have main windows and when a data comes from another thread, I need to show it in another screen for 2 seconds and then go back to previous screen. Screens has many components so I made a simple version to demonstrate my purpose.

Data comes from another thread successfully I can change the text of label. However I can not make disappear the old one and apeear the new one. 

```
from PyQt5.QtCore import QThread
from PyQt5.QtWidgets import QApplication,QMainWindow, QLabel, QWidget, QGridLayout, QVBoxLayout, QGroupBox
from PyQt5.QtGui import QTextDocument
from PyQt5 import QtCore, Qt
from PyQt5.QtGui import QIcon, QPixmap, QFont
from time import strftime 
import datetime 
from babel.dates import format_date, format_datetime, format_time
import sys
import worker
import time

class Form(QWidget):

    def __init__(self):
        super().__init__()
        self.label_main = QLabel("Welcome")
        self.label_uid = QLabel("Exit") 
        self.left = 0
        self.top = 0
        self._width = 480
        self._height = 800

        self.layout_main = QVBoxLayout()
        self.layout_access = QVBoxLayout()

        self.obj = worker.Worker()  # no parent!
        self.thread = QThread()  # no parent!
        self.obj.return_uid.connect(self.onCardRead)     
        self.obj.moveToThread(self.thread)
        self.obj.finished.connect(self.thread.quit)
        self.thread.started.connect(self.obj.get_uid)
        self.thread.start()

        self.initUI()

    def initUI(self):
        self.setLayout(self.layout_main)
        self.layout_main.addWidget(self.label_main)
        self.setWindowTitle('Main Thread')
        self.show()

    def secondUI(self):
        self.setLayout(self.layout_access)
        self.layout_access.addWidget(self.label_uid)
        self.setWindowTitle('Access Thread')
        self.show()

```