I'm not sure you still understand what it is he's asking for. He wants to change the icon of the bookmarks menu button (I think he means the button that shows a drop-down list and not the one that opens the sidebar; please clarify).
LOL! Thanks for the illustration. Yes, that is what I am trying to do. I want to change the ugly, gray Bookmarks Menu that shows a drop-down list of my Bookmarks into a yellow star, which I can place on my toolbar. One icon, one yellow star, that's instantly recognizable, so I know which one has my Bookmarks. The way it is done in the Australis mockups, but without the Australis theme. I have tried the Australis extension and the Classic Tabs user style , but I don't really like it. I tried the Custom Buttons extension, but it never works consistently. There must be bugs with newer versions of Firefox. Can anyone try Custom Buttons and create one like I want? See if you can actually get it to work all the time, cause it only works sometimes for me.