User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.5) Gecko/2008120122 Firefox/3.0.5 Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.5) Gecko/2008120122 Firefox/3.0.5 according to http://www.w3.org/TR/CSS21/visuren.html#floats even if the floated box is after some text in the containing block, it should not break to a new line but push aside the previous text and attach itself to left of the containing block edge's and the pushed aside text should re-flow to the right of the floated box. Reproducible: Always Steps to Reproduce: 1. <P>a<SPAN style="float:left">b</SPAN></P> OR 2. <P>a<SPAN style="float:right">b</SPAN></P> Actual Results: the floated box breaks to a new line. Expected Results: the floated box should remain in the line-box. for left float if it comes after some text it should push that text to its right after attaching to the containing block's left edge. for right float if it comes after some text it should remain in the same line-box and only be attached to the right edge of the containing block. Safari 3.2.1 and Opera 9.63 render it correctly. I am sure this bug is reported many times since I found its reports in many web pages except bugzilla, and the reason that it cannot be found in bugzilla is its buggy search engine!

Maybe you didn't find it in Bugzilla since it's marked RESOLVED-FIXED, since it's fixed on mozilla-central and in Firefox 3.1 alphas. The state of bugs in bugzilla tracks their state in the development code, not the releases.