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After my adventures with making Dojo 0.3 work inside of a Plone template, I was preparing to continue my work with the tree widget, but first I had to test that my version of ZPDojo worked ok with other browsers and operating systems.

I use Linux and Firefox, so I needed Mac and Windows tests. A colleague helped me test on Firefox and Safari on his Mac OSX workstation and then someone lent me a Windows machine to try out my template on IE6.

Well, the tree worked fine on both Mac browsers, but I was really surprised to see the result on IE: not only did my template not work, the browser choked on the whole template and couldn't even show it, any attempt to access any page on my Plone site resulted in a blank page and an alert box telling me that the page had aborted loading due to a mysterious error 80004004.

As you may know, Internet Explorer error messages are among the most helpful messages ever written, so a quick google search led me to a page which shockingly explained to me that error 80004004 means that the request was aborted for some reason.

Thus enlightened, I decided to debug the dojo.js code and find the line or lines that made IE throw its hands up in frustration. After fiddling around for a couple of hours, I found the offending code:

try{
    if(dojo.render.html.ie){
        document.namespaces.add("v",
                "urn:schemas-microsoft-com:vml");
        document.createStyleSheet().addRule("v\:*", 
                "behavior:url(#default#VML)");
    }
}
catch(e){
}

What's weird about this is that the code is wrapped in a try-catch block, but the browser crashes anyway. Other than the fact that this code only gets called when using IE and that it has something to do with the Vector Markup Language, I have no idea how to fix this, so I used my ever faithful comment-out-the-line strategy on the addRule line, commited the new version of my product, reloaded and closed my eyes.

It Worked. Finally I could use my tree widget in Plone on all platforms and, as I happily dragged tree branches from one tree to another, I quickly decided that I won't need VML in the foreseeable future.

Still, if anybody knows what this rule is for or why it only crashes with Plone and works ok everywhere else, I will be much obliged.