Areas are a way to restrict the size of the canvas. You can create areas by using the area tool. If you click on the background you can open the area list dialog using the context menu.
Creating and deleting areas
Use the area tool to create an area. Areas cannot overlap. After you created an area you need to name it.
Click on the area if you want to modify it. You can also use the area dialog.
You have a few options in this menu:
Enter area: Enter the area. You cannot paint outside of the area. Exit the area by clicking on the background with the area tool.
Name: Change the name of the current area
Export: Export this part of the canvas as an image
Delete: Delete this area