People seem to have problems understanding how the android support actually works, so I'll explain a bit.

So, Alien Dalvik is an android emulator/virtual layer and the apps actually think they are running in legit android phone. That's how google play was hacked to work, and why it wants to install google services such as voice search etc.

For example, the WhatsApp (in which people have problems using) works just fine. Sounds, push notifications, popups all work. However, if you have the WhatsApp "on top of the emulator", it will think it's running on an android device and is currently open, as the Jolla won't (can't?) send information about screen turning off to the emulator, and you won't get notifications.
However, if you run WhatsApp "behind" some other application, it will send push notifications etc. just fine. This works for every application.

Myself, I use launcher as a solution. I installed GO Launcher EX from Play store and after I move to another app, I always change back to the launcher first. Then the apps think they are running in the background and will send notifications fine.
Also, as the emulator works like an android device, the task manager/application killer apps work just fine. Though, it seems my Spotify app keeps on restarting itself in the background for some reason.