Comment 37 for bug 274065

(In reply to comment #33)
> This crash goes away if I back out the fix for bug 445890
> ("XMLHttpRequest.responseXml not accessible from signed remote XUL code").
>
> FoxyProxy uses XMLHttpRequest to load a PAC file, load strings from a chrome:
> URI, and load an .xml settings file out of the prefs. I don't know what
> XMLHttpRequest and multiple instances of the file protocol handler have to do
> with crashing on SSL connections.

I don't know if this helps, but FoxyProxy does define a custom protocol handler (see components/relativeprotocolhandler.js). It is used to handle PAC files specified with the FoxyProxy-specific scheme "relative://" Although this crash occurs when accessing SSL connections, I thought I'd mention the custom protocol handler since it's not obvious to those unfamiliar with FoxyProxy and *is* related to protocol handlers.

From the FoxyProxy help:

For PAC files on an ftp server, use the ftp:// scheme. For example, ftp://leahscape.com/path/proxy.pac. You can also use http://, https://, file:// and any other supported scheme. Finally, if you need to refer to a PAC file on the local file system using a relative path, you can use the special FoxyProxy relative:// scheme. This is useful if your PAC file resides on a thumb drive. Supported relative paths are documented here (http://foxyproxy.mozdev.org/relativescheme.html). Special strings in the relative:// URL you specify are replaced with their corresponding values. For example, relative://ProfD/pacs/proxy3.pac points to the file proxy3.pac in the subdirectory of the Firefox profile directory named pacs/. With Portable Firefox on Windows, the Firefox profile directory is always a relative path because the drive letter can change across computers. Please note that special strings (ProfD, Home, TempD, etc.) are case-sensitive."