This GUI application is intended for MacOS. It is create in MacOS using <pyinstaller -F main.py>  command. The first window displayed after running the execution file is just the top left buttons. (Maximise, minimise, close)



Menubar Properties:

Functional

File->Open Image : Prompts the user to select an image file to view. This displayed image will automatically fit to the window size as it is enlarged or minimized.

Semi-Functional
File->View/Keep Aspect Ratio : Prompts the user to select an image file to view in its original aspect ratio. The image in the display window resizes while keeping the window dimensions same. 

Warning: This functionality does not keep the aspect ratio enabled. Once the window size is changed, the image does not maintains it aspect ration.