I've added two external tools: PUTTYGEN and WinSCP. But I can't get them to reliably and consistently appear on the External Tools Toolbar.
Sometimes only one is displayed, sometimes both, and other times none of them appear on the toolbar.
Doing some experimentation while logging this issue, it seems I can force-rotate through these 3 possible states by repeatedly doing this:
Tools -> External Tools
Closing the External Tools panel