You can reduce the clutter in your task bar by opening Firefox’s Add-ons and Download managers in the sidebar rather than a separate window. To do this:
- In the Bookmarks menu, select Organize Bookmarks… to open the Bookmarks Manager.
- Press the New Bookmark… button in the toolbar.
- Enter an appropriate name for the bookmark, for example Downloads.
- Enter chrome://mozapps/content/downloads/downloads.xul in Location.
- If you want, you can assign a keyword like dls to be able to open the
download manager from the location bar, however it won’t open in the sidebar but the main content area.
- Check Load this bookmark in the sidebar.
For the Add-ons manager, enter chrome://mozapps/content/extensions/extensions.xul in Location, instead.
You can also open the Bookmarks Manager in a tab, repeat the steps and enter chrome://browser/content/bookmarks/bookmarksManager.xul in Location, and, of course, don’t check Load this bookmark in the sidebar.
Then place the new bookmarks in a handy place such as top in the bookmarks menu or the Bookmarks Toolbar.