Hi dplanet
I can confirm this issue because I had the same problem when working with composer setup a while ago. I gave up on this bcause i did not get any help. I read in the forum that only few people would create composer pages like this and developer use xml when a theme is installed.
In the documentation you will find old information, - when trying to find updated info you won’t find anything, or you land on a generic documentation landing page. So don’t expect that you’ll get help here. I guess its a bug.
«setup on child pages» works fine even though there is very little info about it. Here it is mentioned:
but it doesn’t say why the dialogs stay on the page until you click it away.
Regards
Coby