From the Tabular Editor window, select the Transitions menu, then click
Add Global Self-Loop, or from the toolbar click on the Add Global Self-Loop button .
This will open the Self-Loop Transition Editor dialog box.
By default, the window only shows events that have not been used. This can be changed by unchecking the Only show unused events checkbox. Select the event you wish to use from the list and click OK. The global self-loop will be added to the Global Self-Loops pane. This will create a self-loop for every state of the DES using the selected event.