Can I force Safari to show the toolbar in login windows? When I buy something on a website, Safari often opens a popup window for payment (e.g. for logging into PayPal). 

This popup doesn't have a toolbar, which means my password manager extension (1Password) is not visible and I can't autofill anything. In the menu bar, there's no command View->Toolbar. How can I get the toolbar to show up?
Use the 1Password autofill keyboard shortcut Command + \ to fill the login information.

You don’t need the toolbar visible in order to invoke 1Password. Heck, you can even get rid of the 1Password extension from the Safari toolbar and work solely with this keyboard shortcut.

This keyboard shortcut is set by default by 1Password.