In DEX you can add graphical rectangles. In schematics they have no electrical significance. However, in PCBs they have significance if they are placed on electrical layers such as the top or bottom layer; here they will leave copper traces and will provide an electrical connection to everything that is connected to them.
Rectangles have a width and height.
Rectangles also have color and can be semi-transparent. It is even possible to define an invisible rectangle. If you have snap to objects enabled objects will snap to invisible lines.
Rectangles can also have a line style as shown below.
See Fill Styles and Line Styles for more styling information.
Sample rectangles