Even though this is quite old, i have decided to answer this article as it still shows up as the first result on google when searching this topic.

I strongly advice against cloning the ootb widget as you will shift responsibility of maintaining the widget from ServiceNow to yourself. You also will not even receive a notification if the OOTB widget is beeing patched as cloned widgets do not show up in the Upgrade Records (this might have a security impact as you also dont receive hotfixes!).

Please use the Client Side Buttons Widget (less than 40 lines of code) which is added in parallel to the OOTB form widget: How to enable Client Side UI Actions on the Service Portal