I have created mutlifield dialog in classic UI AEM 6.2 using fieldConfig widget (xtype=multifieldpanel).And it is working fine.But I get error when I do the same in 6.3 classic UI.Anyone please let me know why does this occur ! Or is this deprecated in 6.3 classic UI

Hi,I want to trigger my customized workflow on activating a page.I surfed a lot and came to know that Siteadmin.Actions.js file has to be overriden.If this is the right approach, please help me what changes has to be made in the file.