<frame src=

   <frame src=

If I make a file on my hard drive as follows: '''< html>''' '''<title>addons.mozilla.org in frames</title>''' '''<frameset cols="50%,50%">''' '''<frame src= "http://addons.mozilla.org/en-US/thunderbird/addon/13564/">''' '''<frame src= "http://addons.mozilla.org/en-US/thunderbird/addon/2313/">''' '''</frameset>''' '''</html>''' ... and then open this file in Firefox, the frames seem to be redirected to about:blank. That is, if I right-click in one of the frames and choose This Frame > View Frame Source, the titlebar of the resulting window says "Source of: about:blank." The desired operation of Firefox is that the target page should not redirect to about:blank, but should be displayed within the frame. I loaded one of the target URLs (addons.mozilla.org) in its own browser window and viewed the source. I wanted to find out whether the page might have contained some JavaScript that redirected the browser to about:blank if the page was loaded in a frame. But Firefox's Find function did not locate either the text "frame" or the text "about:blank." I did a search in Bugzilla for just "frame about:blank," which returned over 34000 bugs. I sorted by ID and looked at the summary lines of the most recent few hundred bugs, but none seemed to match the problem I'm having. The problem did not happen until I upgraded from a recent prior version of Firefox (3.6.8?) to 3.6.12. When the addons.mozilla.org pages in question are loaded in their own browser windows, they redirect to HTTPS. So I tried using frames to load some other HTTPS sites, which loaded fine in frames. I appreciate your help.