PADS I/O Designer supports different symbol backgrounds. In addition to the default rectangle, you can choose among several other backgrounds, such as mux. To change the background, open the Properties window for the symbol, and change the Background property there.
Backgrounds may be customized. To edit the background of the current symbol, check the Symbol > Edit Background option. All symbol elements, except for the background, are hidden. In this mode you can use any graphical elements to change the appearance of the background. To switch back to normal symbol editing, uncheck the Edit Background option.
You can save the changed background in order to use it in other symbols. Use the command Symbol > Export Background. This option displays the standard Save dialog, in which you can choose the background file name. Backgrounds should be saved to the shapes subdirectory of the PADS I/O Designer installation directory, since in the Properties Window only backgrounds found in this subdirectory are accessible.