To make optimum use of the content in this book, please bear the following points in mind:

• All the recipes in this book were developed using Python 3.7 on a Windows 10 64-bit OS. They have not been tested on any other configuration. As Python is a cross-platform language, the code from each recipe is expected to run everywhere.
• If you are using a Mac, it does come with built-in Python, yet it might be missing some modules such as tkinter, which we will use throughout this book.
• We are using Python 3.7, and the creator of Python intentionally chose not to make it backward-compatible with Python 2. If you are using a Mac or Python 2, you might have to install Python 3.7 from www.python.org in order to successfully run the recipes in this book.
• If you really wish to run the code in this book on Python 2.7, you will have to make some adjustments. For example, tkinter in Python 2.x has an uppercase T. The Python 2.7 print statement is a function in Python 3.7 and requires parentheses.
• While the End of Life (EOL) for the Python 2.x branch has been extended to the year 2020, I would strongly recommend that you start using Python 3.7 and later.
• Why hold on to the past, unless you really have to? Here is a link to the Python Enhancement Proposal (PEP) 373 that refers to the EOL of Python 2: https://www.python.org/dev/peps/pep-0373/.

You can download the example code files for this book from your account at www.packt.com. If you purchased this book elsewhere, you can visit www.packtpub.com/support and register to have the files emailed directly to you.

You can download the code files by following these steps:

1. Log in or register at www.packt.com.
2. Select the Support tab.
3. Click on Code Downloads.
4. Enter the name of the book in the Search box and follow the onscreen instructions.

Once the file is downloaded, please make sure that you unzip or extract the folder using the latest version of:

• WinRAR/7-Zip for Windows
• Zipeg/iZip/UnRarX for Mac
• 7-Zip/PeaZip for Linux

The code bundle for the book is also hosted on GitHub at https://github.com/PacktPublishing/Python-GUI-Programming-Cookbook-Third-Edition. In case there's an update to the code, it will be updated on the existing GitHub repository.

We also have other code bundles from our rich catalog of books and videos available at https://github.com/PacktPublishing/. Check them out!

We also provide a PDF file that has color images of the screenshots/diagrams used in this book. You can download it here: https://static.packt-cdn.com/downloads/9781838827540_ColorImages.pdf.

There are a number of text conventions used throughout this book.

CodeInText: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: "Here is an overview of the Python modules (ending in a .py extension) for this chapter".

A block of code is set as follows:

action = ttk.Button(win, text="Click Me!", command=click_me)
action.grid(column=2, row=1)

Any command-line input or output is written as follows:

pip install pyqt5

Bold: Indicates a new term, an important word, or words that you see on screen. For example, words in menus or dialog boxes appear in the text like this. Here is an example: "Click on the File menu and then click on New."