We are aware that in the latest Android version KitKat, there are changes to how SMS applications must behave, so they are able to modify messages.

Since Text Talk mostly targets “down level” Android versions, you currently won’t be able to Mark Read or Delete messages from within Text Talk under KitKat.

We are working on an update for this, but it requires Text Talk to also handle MMS messages, so it can become a “default” SMS application.