Your proposal aimed into the right direction, thanks for that.
I now solved the challenge (with the help of Qlik Architect) like that (maybe this helps some fellows in the future who are that desparate as I was :-) ):
- Disable Security Rule CreateAppObjectsPublishedApp
- Create new Security Rule with similar name (ie CreateAppObjectsPublishedApp_disableEditButton) with same settings as rule CreateAppObjectsPublishedApp
- Amend Conditions with "and resource.app.@DisableEditButton.Empty()"
- Create Custom Property for Apps (ie name "DisableEditButton") with one Value "Disable"
- Now all apps where you want to hide the EditButton (and consecutively prohibit sheet duplication) need to be equipped with Custom property value "Disable"
Hope that helps