[jeroenhd]

I can see the issue, but SYSTEM_ALERT_WINDOW isn't a permission you'd normally give to an app. You can probably trick some users into giving that permission, but it's not easy and Google Play will probably kick your app out of the Play Store if you try to use it in the first place.

Abuse from system apps is a potential threat but you can't really do much about those. System apps can bypass all manners of restrictions, I'm not sure if clipboard access is something to be particularly worried about when system apps can already read your entire SD card and bypass app firewalls/VPNs.