The name of the Webroutine to be invoked when an item in the weblet is selected.
Note: It is not good user-interface design to initiate actions from the click of a dropdown. Devices such as a push button, menu item or anchor (hyperlink) should be used to accomplish this.
The name of a Webroutine in single quotes. The Webroutine must exist in the WAM specified in the on_change_wamname property. A list of known Webroutines can be displayed by clicking the corresponding dropdown button on the property sheet.