Ordering service with global variables

Im working on a project and im making an ordering system currently i’ve managed to design the UI and each button/checkbox/combobox to add a value into the final price textfield, but they only add value to there own local item, so nothing is really getting added, i also have a listbox that doesn’t work but it purpose is to show whats in the order and the “add to order” button doesn’t actually do anything since every time i click a button/checkbox/combobox it adds it regardless if i used the add to order function.

so i need help making my software make a pizza order, so select the size which adds a price, and check boxs that will allow toppings to be added, and finally a button that adds all this into the listbox and the order value textfield.

What is your question? Don’t want to sound rude but you seem to be struggling with beginner stuff. Have you read the documentation?

And no, don’t use global variables.