toolbar as plugin?

The documentation on how to write different things needs a bit of an update. For example, the phrase “However you can only use them as effects to alter sound or analyse it, not to add new toolbars to Audacity.”, does that apply to " LADSPA, VST and Vamp" only or all plugins?

If I want to try and write a toolbar, is that possible with a plugin or only by writing in the code base?

That can only be done by modifying the code base.

OK, thanks!