firefox тоже держит.
вот пример чаво вставить в html
<div id="Layer1" style="position: absolute; width: 400px; height: 180px; z-index: 2; left: 140pt; top: 0pt;">
<embed style="" adblockframename="adblock-frame-n0" adblockframedobject2="true" src="floating.swf" FlashVars="backAlpha=50" quality="high" bgcolor="#cccccc" allowscriptaccess="sameDomain" type="application/x-shockwave-flash" wmode="transparent" pluginspage="http://www.macromedia.com/go/getflashplayer" align="center" height="180" width="400">
<div id="adblock-frame-n0" adblockframe="true" style="margin: 0px; padding: 0px; overflow: visible; width: 1024px; display: block;">
<div style="height: 0px; width: 100%; overflow: visible;" align="left">
<div style="border-style: none ridge ridge; border-width: 0px 2px 2px; padding: 1px; vertical-align: bottom; opacity: 0.5; background-color: white; position: relative; z-index: 900; width: 48px; height: 15px; cursor: pointer; overflow: visible; -moz-border-radius-bottomleft: 10px; -moz-border-radius-bottomright: 10px; top: 0px; right: -5px;" align="center"><span style="font-family: Arial,Helvetica,Sans-serif; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; line-height: 140%; text-align: right; text-decoration: none; opacity: 1.5; color: black;">Adblock</span>
</div>
</div>
</div>
</div>