This document contains code for several different programs written in Gambas including:
1. A billing program that allows a user to add items, quantities, and prices to a grid and calculates subtotals.
2. A basic calculator program that includes number buttons, arithmetic operators, and functions like square root.
3. A program that calculates the percentages of different products in a total.
4. A program that draws circles on a form and allows changing the radius size.
5. A screen saver program that draws random shapes on a form with changing colors.