Minox

From the latest versions of Android, to read the notifications the user must manually approve this choice, therefore when starting the app you have to open the notification authorization list and let him select it. To achieve this, as far as I understand, you need to set the "android.permission.BIND_NOTIFICATION_LISTENER_SERVICE" permission in the Manifest file (I do this in the project options), as described here: NotificationListenerService, and then at runtime open the permissions page to ask the user to activate them, using this entry: Settings Here a procedure in java: notificationlistenerservice I know my approach is wrong, but i don't understand where. For example, when I asked permission for brightness in other applications, I used the same approach, and it worked.

To improve fluidity I would use a thread, so as to limit the pauses due to the execution of something else

This is because the actual size of the rectangle does not change. Try inserting the main rectangle in a Layout of the same size, and when you work with the TrackBar change the size of the Layout appropriately. Or resize the main rectangle directly, instead of acting on the "Scale" property