So I was trying to understand how prebuilt panels worked so I can use it in HTML dashboard. So first I created a dashboard with prebuilt panels using simplexml I had these different panel scenarios. I added one with custom drill-down (redirects to search in new tab with custom search). After saving it I just clicked the convert to HTML option provided at the top right. In the converted dashboard it lost the custom drill-down and sets it to default drill-down search. Not sure if it is supposed to do this.