manual/include/working-with-ardour-built-plugin-editors.html

<p>
  To view a plugin editor, double-click on the plugin within the 
  <a href="/working-with-plugins/processor-box/">processor box</a>. 
  A new window will appear showing the editor/GUI for the plugin.
</p>  
<p>
  If a plugin does not have its own GUI, Ardour will construct a
  <dfn>generic plugin editor</dfn> from a small set of common control 
  elements. Ardour will do this even for plugins that have their 
  own, if you disable <kbd class="menu">Edit &gt; Preferences &gt; 
  GUI &gt; Use Plugins' own interface instead of Ardour's</kbd>
</p>
<p>
  You can temporarily switch to the generic UI by context-clicking on 
  a processor and selecting <kbd
  class="menu">Edit with generic controls</kbd>. This will be necessary to
  access the <a href="/automation/">plugin automation controls</a>.
</p>
<p>
  In the generic UI, you can re-set any controller to its default by
  <kbd class="mod3 mouse">Left</kbd>-clicking on it.
</p>