Hi Paul,
In my cases (plural) every TB install has this problem. I am using different hosting providers different themes, any and all browsers and also the standard TB themes. Result is the same. This "problem" exists for a long time now and did not start with TB version 1.3.
Since this is not a real problem but more some sort of inconvenience I don't care much personally, but my clients do.
So, any suggestion how to fix this minor problem? Anyone? Please and thank you!