**Multi-Threaded Work - Running long tasks inside of a GUI** This program demonstrates one way of using a combination of Python's Thread and Queue objects to implement a GUI that performs work that takes too long to directly perform inside of the event loop. An example use would be if you have a button that you want to use to start some code that will take several seconds to run, then this technique is a good pattern to use. Take a moment to examine the code dealing with the Thread and the Queue. These constructs are nothing to fear as the amount of code that uses them is only a handul of lines of code are needed. And they are simple enough that you'll be able to understand them. ***"Thread-safe"*** - This is an important term to consider any time you are using threads in your program. There are 2 things to check out: 1. You must make sure that the calls you make from your thread are OK to call from a thread 2. If you are running multiple threads, then the calls you make must be "thread-safe" The authors of libraries you are using often tell you if their code is "thread-safe". PySimpleGUI code is not thread safe. For the tkinter version (i.e. plain PySimpleGUI versus PySimpleGUIQt), you cannot run PySimpleGUI as a thread. To put that in simpler terms, you cannot make any calls into the PySimpleGUI package from a thread. For example, you cannot call `update` for any of your elements from a thread. This is why you see the updates happening from the main thread only. Screenshot: ![SNAG-0491.jpg](/api/files/5da0877e2299175412c57964/snag-0491.jpeg "SNAG-0491.jpg")