I have created a custom multifield widget (CustomWidget.js) in my clientlibs, which is integrated into a custom tab in the page properties.
fieldDescription="Press + to add more information"
This works fine when I am on the page and open the page properties from the sidekick.
But when I am on the siteadmin page with the content tree and rigth klick on a page and choose 'properties' the multifield doesn't work. Browser console says:
Uncaught cannot create Component: xtype 'customWidget' not found and no default supplied
How can I make the JS for the widget being loaded on the siteadmin page?