This extension worked perfectly, up until today. I accidentally moved the file containing my header image. I put it back where it was, but the theme is now black. So, I created a new custom theme, but it does not have a save button. There is nowhere to save my custom theme. And, if I open a link in a new window, rather than a new tab, the custom theme is not applied. The only way to get it back is to redo the customization. I am frustrated. This was a great extension, until Firefox screwed it up.