Samsung versus Google: Can status icons be green? Google's docs say "no."

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Samsung has issued another update on the explosive Galaxy Note 7 situation, this time informing consumers how they can differentiate fixed devices from unfixed devices. Through a software update, Samsung says it is going to give non-explosive Note 7s a green battery icon, giving people a quick way to tell a Note 7 is no longer dangerous. There's just one problem with the green battery icon: it's against the rules.

The core Android platform is open source, but Google's Android apps—like the Play Store, Gmail, YouTube, and others—must be licensed from Google. Licensing these apps means adhering to several terms from Google, including complying with the Android Compatibility Definition Document (CDD), which in turn ensures that devices are "Android compatible." APIs need to work the way developers expect them to, hardware needs to meet Google's minimum requirements, and OEMs need to follow Google's security recommendations.
In the CDD, Google also defines some of the interface design—usually the parts apps need to interact with, like the System UI and shared theme assets. This includes mandating the color of the status bar icons, which seems to throw a wrench in Samsung's publicized plans. The section titled "3.8.6. Themes" reads (emphasis ours):

Android supports a variant theme with translucent system bars, which allows application developers to fill the area behind the status and navigation bar with their app content. To enable a consistent developer experience in this configuration, it is important the status bar icon style is maintained across different device implementations. Therefore, Android device implementations MUST use white for system status icons (such as signal strength and battery level) and notifications issued by the system, unless the icon is indicating a problematic status or an app requests a light status bar using the SYSTEM_UI_FLAG_LIGHT_STATUS_BAR flag. When an app requests a light status bar, Android device implementations MUST change the color of the system status icons to black [Resources, 34].

Google spells it out pretty clearly: status bar icons have to be white. They aren't allowed to be green, which is the color Samsung plans to use in a future update.

It might be a little silly to mandate specific colors for certain parts of the user interface, but users can change home screen apps and wallpapers, and apps often add icons to the status bar. To preserve readability, it's easier to just mandate a color and have the various interoperable parts of the Android ecosystem design around that. Before requirements like this, it wasn't unheard of to see unreadable combos like dark text or icons on a dark background because colors from device to device varied so much.

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One problem area immediately comes to mind: the "My apps" section of the Google Play Store turns the background behind the status bar green. That's going to look pretty bad with a green battery icon.

So far Samsung has only announced the change; the new icon hasn't made it out to consumers yet. According to the leaked contracts OEMs sign with Google, every Android software update must be sent to Google for retesting against the CDD. If Samsung didn't tell Google about its plans to change the status bar icon, Google will know once it gets a copy for approval. We should soon find out if the compatibility docs have any bite.