App doesn't open when it's in background - Need to request SYSTEM_ALERT_WINDOW permission

[tanzil114]

Please see:
https://developer.android.com/guide/components/activities/background-starts

If we want the app to open any other app while it is background, our app needs to have SYSTEM_ALERT_WINDOW permission. The plugin DeviceApps doesn't check for this, and returns true on calling openApp method, even though the app doesn't get opened. Once we have the permission, it opens up alright.

https://developer.android.com/reference/android/Manifest.permission#SYSTEM_ALERT_WINDOW