What does the dotted white box around a variable name indicate?

Question

I've just noticed that sometimes a dotted white box that appears around variables while typing their name. What is this supposed to indicate? A quick Google only turned up lots of completely unrelated results

In the below image the cursor is at the end of StatusByte, which has just been typed in and which previously used a different name. The change is not done as a "Rename" (Ctrl+R, Ctrl+R) and the variable is not yet used anywhere else at this point. The box disappears, not when I move the cursor away, but when the cursor is moved elsewhere and typing begins.

I am using VS 2017 15.3.1, only having recently updated from a 15.2.x version. I don't think this was occurring in that previous version but may just not have noticed it. This shows in Visual Basic, I have not had chance to check with other languages yet.

Answer 1

This box appears while you are changing a variable, method, class or namespace name in Visual Studio 2015 and Visual Studio 2017 for C# and Visual Basic.

(I have an extension that hides it: Plain Rename.)