Thank you for your post.
I am able to replicate the problem on Windows XP, Mac OS X 10.5.8 and Mac OS X 10.6.3.
You don't even need to create a script. Just selecting "New Window" from the Window menu causes the problem.
I have forwarded your post along with my findings to our Development and Software Quality Assurance (Testing) departments for review and confirmation. I will keep you posted.
Since there is no Get function to capture the current tab control, a workaround is difficult. Off the top of my head, I would make buttons as the tab controls that captures the name of the tab control, and then you can pass it as a parameter to a New Window script. If you need clarification and/or help, please let me know.
As a work around since you have Advanced is to capture which object is the front tab panel using GetLayoutObjectAttribute ( ) and a couple of If / Else and envoke this script via a custom menu that overrides the New window menu item.