The Modify Shape dialog box enables you to specify shape you want to apply to a selected object(s).

To set a predefined shape, just select the shape from the Predefined Shapes list.

To save your custom shape, set a new shape by dragging the select handles before entering the dialog box. Open the dialog box and click the Save As… button. The Save As dialog box will open, where you can enter a new name for the Shape, or choose to overwrite an existing one from the list of predefined shapes.

To delete a shape from the library, select it and press the Delete button.