Today's DC update means that questions with an accepted answer have the background of their answer count box shown differently. In the screenshot below, the first question has received 3 answers but the OP hasn't marked any of them as accepted. The second has now answers, and the third has two, one of which has been accepted by the OP:

That's good, but when I click into the third question I am no longer shown which of the answers the OP accepted:

 

Prior to the DC update I would have seen a green checkmark alongside the accepted one.

Is this change deliberate, or an unintended side-effect of you no longer showing the checkmarks when they're not clickable (which means they're hidden from everyone except the OP)?

The announcement post includes the following information:

It includes hundreds of bug fixes and new features, including:
*        DeepSee improvements to the Folder Manager and Dashboard Filters
*        iFind and iKnow improvements like coocurrence search, REST API extensions, and performance when building iKnow domains
*        Improved XML VDoc performance in Ensemble
*        Caché Nodejs now supports Node 7

Unless you upgrade to 2016.2 or beyond you can't yet use Atelier as your code editor, so integration with file-based source code management (SCM) tools such as Git or Perforce isn't so straightforward. Deltanji works natively inside Caché 2008.1 and later and integrates easily with Studio (as well as with Atelier). The Solo edition is free.

Or maybe when you write "Configuration management tools" you aren't referring to SCM?

In the same way as you create an instance of any class:

ENSDEMO>set oInst=##class(Demo.Loan.FindRateProduction).%New()
 
ENSDEMO>zw oInst
oInst=<OBJECT REFERENCE>[1@Demo.Loan.FindRateProduction]
+----------------- general information ---------------
|      oref value: 1
|      class name: Demo.Loan.FindRateProduction
| reference count: 2
+----------------- attribute values ------------------
|  AlertActionWindow = 60
|AlertNotificationManager = ""
|AlertNotificationOperation = ""
|AlertNotificationRecipients = ""
|    ShutdownTimeout = 120
|      UpdateTimeout = 10
+-----------------------------------------------------
 
ENSDEMO>

By looking at the code of the InstanceGUID method in the %SYS.System class we can see where it's stored:

/// Returns instance GUID.
/// <br>
/// An instance GUID is a 16 byte (128 bit) globally unique identifier, assigned per instance of Cache installation.
ClassMethod InstanceGUID() As %String
{
    s ns="^^"_$zu(12)
    if ('$d(^[ns]SYS("INSTANCEGUID"))) Set ^[ns]SYS("INSTANCEGUID")=$system.Util.CreateGUID()
    Q ^[ns]SYS("INSTANCEGUID")
}

It's in ^SYS("INSTANCEGUID") in the CACHESYS database.

USER>w ##class(%SYS.System).InstanceGUID()
C59DD3E8-8474-4045-B252-1AF1A0D94F3C
USER>w ^|"%SYS"|SYS("INSTANCEGUID")
C59DD3E8-8474-4045-B252-1AF1A0D94F3C
USER>w $zv
Cache for Windows (x86-32) 2016.2.1 (Build 803U) Wed Oct 26 2016 13:33:05 EDT
USER>

However I don't know what might happen if you change it. Best check with InterSystems.

I don't know if this is related, but recently when I've been posting images in new articles, or in answers or comments, I sometimes upload my standard filename (Capture.PNG) but the image that appears in the DC editor window is wrong. It often seems to be one that I've previously uploaded, though not necessarily my most recent previous upload. I delete it in the editor, repeat the upload, and it's usually OK the second time. I recall once having to do two retries. I'm using Firefox 53.0 on Windows 10.

Anyone else seeing this kind of event?