I have created tons of add-ins in the last years using the add-in wizard of Visual Studio, and the other day I wanted to use a project name with a ‘.’ dot character in the name. I noticed this bug that I have reported to Microsoft Connect:

Checkbox to create CommandBar disabled in add-in wizard if name contains “.”
https://connect.microsoft.com/VisualStudio/feedback/details/789323/checkbox-to-create-commandbar-disabled-in-add-in-wizard-if-name-contains

and I have documented in the MZ-Tools Series articles:

BUG: Checkbox to create CommandBar disabled in add-in wizard if name contains ‘.’
http://www.mztools.com/articles/2013/MZ2013003.aspx

The curious part is that it worked in Visual Studio 2005, but was broken in Visual Studio 2008 and the bug persists.