Hello Roger,

Projects in solution are in alphabetic order. This is a product limitation.
As far as I know, we cannot customize the order.

If you have concern on this behavior, you can also post the issue to our
Connect feedback portal. Product teams maybe consider adding it to the next
version of Visual Studio.
http://connect.microsoft.com/VisualStudio/
Improving the quality of our products and services is a never ending
process for Microsoft.:)

Have a great day,
Best regards,

Wen Yuan
Microsoft Online Community Support
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