User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9b5pre) Gecko/2008030904 Minefield/3.0b5pre Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9b5pre) Gecko/2008030904 Minefield/3.0b5pre Clicking the rendering mode icon opens a tiny browser window in the top left corner with a File Not Found message -- about jar:file:///C:/Program Files/[my install dir]/chrome/browser.jar!/content/browser/pageInfo.xul. It's a really useful feature, and I'd like it fixed soon. Reproducible: Always
What "rendering mode icon" are you talking about? Is it a feature added by some web-development extension?
Created attachment 308527 [details] Screenshot of the icon I am attaching a screenshot of the icon. You tell me what it's part of.
I think it would be easier for you to determine which extension (of the ones you have installed) added that icon than for me to try installing every web-development extension in existence and trying to match your screenshot.
I just launched FF with a new profile and realized that the icon does, indeed, belong to some extension. Marking this as invalid.