I tested the code you sent in your last post and indeed, I was able to reproduce the problem in Safari and Chrome, but only with the Q3 2008 SP1 version of the RadControls for ASP.NET AJAX (version number 2008.3.1125). I was not able to reproduce it before, as I was using the latest version of the suite, namely version Q3 2008 SP2, with version number 2008.3 1314.
That is why, in case you just update your DLL to SP2, you will have no problem specifying the size of the RadToolTip.
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