Why is there a white screen in my python kivy project?

Question

Python

I have a program in which there are 2 image widgets, the program detects a collision between them, but when launched, the program finds a collision, but the whole screen is white, why is that?

code and picture

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.button import Button
from kivy.uix.label import Label
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.animation import Animation
from kivy.clock import Clock
from kivy.config import Config
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.image import Image
from kivy.core import audio
from kivy.core.audio import SoundLoader
from kivy.uix.widget import Widget
import time
#import socket
#sock = socket.socket()
#sock.bind(('', 9090))
#sock.listen(1)
 
 
Config.set('graphics', 'resizable', '0')
Config.set('graphics', 'width', '500')
Config.set('graphics', 'height', '500')




 
class MainApp(App):
    def build(self):
        self.title = 'project123'
        main_layout = FloatLayout()
     
# Label
        name=Label(text ='lbl', font_size='15sp', size_hint =(.5,.5), pos_hint = {'center_x': .5, 'center_y': .5})
        main_layout.add_widget(name)
        """
        wid= Widget(size=(.5, .5), pos=(.5, .5))
        wid2 = Widget(size=(.5, .5), pos=(.5, .5))
        main_layout.add_widget(wid)
        main_layout.add_widget(wid2)
        while True:
            time.sleep(0.6)
            if wid.collide_widget(wid2):
                print("col")"""
        wid = Image(source='man1.png', pos=(.5,.5), color=(.1,.1,.1, 0.5))
        wid2 = Image(source='man1.png', pos=(.5,.5), color=(.1,.1,.1, 1))
        while True:
            time.sleep(0.6)
            if wid.collide_widget(wid2):
                print("col1")

# CODE

        return main_layout
# DEFS
 
 
 
if __name__ == '__main__':
    app = MainApp()
    app.run()

man1.png

Answer 1

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.button import Button
from kivy.uix.label import Label
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.animation import Animation
from kivy.clock import Clock
from kivy.config import Config
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.image import Image
from kivy.core import audio
from kivy.core.audio import SoundLoader
from kivy.uix.widget import Widget
import time
#import socket
#sock = socket.socket()
#sock.bind(('', 9090))
#sock.listen(1)
 
 
Config.set('graphics', 'resizable', '0')
Config.set('graphics', 'width', '500')
Config.set('graphics', 'height', '500')




 
class MainApp(App):
    def build(self):
        self.title = 'project123'
        main_layout = FloatLayout()
     
# Label
        name=Label(text ='lbl', font_size='15sp', size_hint =(.5,.5), pos_hint = {'center_x': .5, 'center_y': .5})
        main_layout.add_widget(name)
        """
        wid= Widget(size=(.5, .5), pos=(.5, .5))
        wid2 = Widget(size=(.5, .5), pos=(.5, .5))
        main_layout.add_widget(wid)
        main_layout.add_widget(wid2)
        while True:
            time.sleep(0.6)
            if wid.collide_widget(wid2):
                print("col")"""
        wid = Image(source='man1.png', pos=(.5,.5), color=(.1,.1,.1, 0.5))
        wid2 = Image(source='man1.png', pos=(.5,.5), color=(.1,.1,.1, 1))

        main_layout.add_widget(wid)
        main_layout.add_widget(wid2)

        if wid.collide_widget(wid2):
            print("col1")

        return main_layout

 
 
if __name__ == '__main__':
    app = MainApp()
    app.run()