If you need additional features in your program which GUI Pie cannot provide, you can add in the additional code under the "more" section. GUI Pie's default options are perfect for first-time users, but to cater to advanced users, the ability to provide your own code to the GUI file will be of use. Want to add a property to a widget that isn't provided? Add that line to the "more" section. Want to add a specialised widget? Add the lines for that in the "more" section.
CAUTION - any errors written in your additional code will lead to errors in the final exported window. This could lead to your window not being able to run. Ensure all additional code is syntactically correct.
To add extra code, open the "more" panel from the ribbon, and put in your code in the entry box. Each new line represents a new line in python - so don't worry if you write an extra long line and it spans over to a new line.
The code written is placed at the very end of the GUI file, but before any custom widgets. This means that any properties changed are the final properties when the code is imported, and custom widgets can reference this code.
If you want to write more than a few lines of code, it may be better to import a dedicated python file. This way, you can use a fully fledged code editor with superior features to the simple GUI Pie text box.
To reference the name of the root window, use the {root} keyword. GUI Pie will replace this with the name of window when creating the file.