Javascript sizes not reliable?

In Safari, why are windows opened via Javascript 2 pixels wider and 1 pixel higher than requested?

I googled for the answer no avail, so made a simple test page, and asked for answers on a (usually quite reliable) local mailing list, but haven’t got an answer. So, I posted the test page to my linklog in the hope of it gaining a wider audience. A few hits, but no answer :-(.

So: now, I’m re-posting the question here to drizzle a little google-juice on the test page, and hope one of my legion of trusty feed subscribers can spring to my assistance.

I suppose a keyword-stuffed rephrasing of the question could be: Is there reliable cross browser way or technique for opening a fixed-size window via Javascript or with DOM browser scripting ( or similar)?