"An Insets object is a representation of the borders of a container. It specifies the space that a container must leave at each of its edges. The space can be a border, a blank space, or a title."
Better yet is GridBagConstraints documentation on how it uses Insets:
This field specifies the external padding of the component, the minimum amount of space between the component and the edges of its display area.
Given GridBagConstraints g, any component added using g will have g.insets.top and g.insets.bottom added to it's preferred height and g.insets.left and g.insets.right added to it's preferred width when determining it's display area. It's display area in the case of a GridBagLayout is the size of it's cell. Note that other components in the same row or column may affect the cell's width or height as well.
Post by:autobot
Once upon a time there were three bears. And they were visted by a golden haired tiny ad:
a bit of art, as a gift, the permaculture playing cards