After I posted a comment saying I'd like to be able to drag and drop my most-used apps to the toolbar, I discovered that you can hit the extension button, right-click on an app's button, and select "pin to toolbar." That works for me: my favorite app...
J:Thank you for your very helpful response. Solution A worked for both Project Gutenberg and IMDB. Web of Science, not, but I haven't set up an account with them, so maybe it would work if I did. For now, I'll stick with Google Scholar. Solution B wo...