Hello, I'm having trouble adding a button to the main toolbar. I'm creating a xul overlay extension but for some reason I can't seem to add the button to the toolbar. I'm able to install it, but not make the button appear. What I'm trying to do is create a toolbar button, that opens a popup containing an iframe. I need exactly what the user Felipe Silva show in this example: http://stackoverflow.com/questions/18506117/create-mozilla-extension-to-display-a-popup-and-iframe-in-it The only difference is that the iframe needs to load an html file packaged with the extension and not some external source. I'd also like to add the button by default to the toolbar but I need to get the button working first. You can download a copy of the extension here: https://dl.dropboxusercontent.com/u/9942366/firebomb.xpi I know this would be easier if I was using the SDK but the toolbar button module requires Firefox 29 which is not stable yet so I prefer doing this way. Any help would be greatly appreciated.