Show broken images in Firefox

Firefox is so "kind" to hide broken images or just displays the alt text without indicating that there should be an image. For regular visitors of your website that's good, because you don't want to be confronted with the red cross from MSIE. If you're a web developer using Firefox like me, you do want to see any broken image, whether it's from the CSS, static images for the design or just a part of the content.

I found a Show Missing Images plugin that does display broken images. Unfortunately it displays all Blogger button images in the editor as broken, so typing this entry felt like walking through my house blindfolded.