I've been testing with the 13.8.21.12 build. There's a new regression I suspect due to the fix for this issue:

http://forum.nevron.com/shwmessage.aspx?forumid=2&messageid=7944

To reproduce:
1) Start the Nevron UI C# examples program and show the Tab Control example
2) Check the "Show Close button on each tab" feature
3) Click the X on a tab which is not the top selected tab
4) The wrong tab gets deleted. Happens in my program too.

Could you please post when the fix for this is in a build that can be downloaded?