In the Inspector window, select the object whose handler you want to rename.
Click Events in the Properties window.
Select the handler name you want to rename, and type the new name.
Alternatively, select the event in the property sheet and click the ellipsis
(...) button to display the Handlers dialog box.
If you displayed the Handlers dialog box, select the handler to rename
in the Handlers list, click Rename, and type the new name for the handler
in the Rename Handler dialog box that appears.