This page is describing two problems with setting the width feature of the window.open method (3rd parameter). Problem one: there's no checking on minimum window with, which may lead to misrendering of the addressbar (google input entry). Problem two: when specifiying the width with a fraction, the width is set to something like 100px and will lead to misrendering of the addressbar.
Real world testcase: startpagina.nl. This is a Dutch directory and one of the top-3 most visted websites in the Netherlands (the wrong behaviour has also been reported to the webmaster of startpagina.nl).
According to Interface Builder the main window (Browser.nib) had the minimal dimensions of width:392px and height:200px (Safari 1.1.1 (v100.1)).