While most companies test their skins of the Android operating system by releasing almost final software to some devices, Sony has been taking a different approach recently. They now release concept versions of Android to get feedback from select users and they keep adding features until it gets close to the build that will be released to a wider audience. For the Concept software based on Android Marshmallow, Sony invited users with an Xperia Z3 or an Xperia Z3 Compact who live in some European countries to sign up for the test and 10,000 of them would be chosen. This software was released very close to the date when Google updated their Nexus devices, so the software looked almost like the stock version of Marshmallow with only a few elements that Sony has been using recently and some of their own apps.
Since then, the software has been updated a couple of times with improvements to the tap to wake function, a new boot animation and the battery icon showing the percentage level, it also got Theme support and the possibility to take a screenshot in the power off menu, the automatic brightness was improved and they has fixed some issues with the email app. Of course, they have been correcting some bugs and issues along the way and some proprietary apps have also been updated. Now, the Xperia Marshmallow Concept is being updated again to build number MDB08M.Z1.2178-somc with further improvements.
The changes on this version include a new version of Sony Email (11.0.A.0.4) and it fixes the badge count, deleting email with back space and a crash when adding attachments. The Home launcher has also been updated to version 10.0.A.0.4 and now it allows to delete most preinstalled apps, even some Google ones, although some made by Sony can't be deleted. Sony Album version 7.4.A.0.12 fixes screen mirroring and a color bug. The update also fixes a problem with WiFi power stats and the BT routing issue. They also optimized the backlight and the proximity sensor, plus German text in the Camera app has been improved. It was also reported that Sony wants Google to add a Reboot button to the AOSP build, as this feature is among the most requested ones, so we will most certainly see it in the final build.