In this chapter, we have learned why using a second thread within a GUI application can be beneficial. We have seen that large tasks can make the GUI look as if it has stopped responding, which can confuse users. After introducing a separate thread, we then eliminated this problem and made the application behave as a user would likely expect.

Using our new knowledge of threads, we then improved our chat application by allowing it to pull in new messages in the background, without disabling the GUI itself while doing so.

Afterwards, we increased the quality of our application by allowing the user to choose their own avatars. We learned how we can use the PIL module to resize and save images, removing any restrictions on the user in terms of choosing the correct avatar size, or the application developer in terms of accommodating any huge images the user may wish to use.

Finally, to improve the social aspect of our application, we added the ability for the user to choose which friends they wanted to be able to contact, and gave them the option to block any other users who they did not wish to speak to any more.

Along the way, we have picked up some new features of SQL, such as UPDATE, SET, and IN, allowing us to manipulate existing rows in a database.

In the next chapter, we are going to cover packaging up applications into executables for different OSes. This will allow people to run them without installing Python. We will also touch upon several widgets which have not been utilized in any of our example applications, but that deserve a mention anyway.