Open a Window in JUCE and put a PluginEditor into it - c++

Question

The tl;dr How do I open a window in Juce to display a plugin Editor?
I am following the Juce AudioProcessGraph tutorial at https://docs.juce.com/master/tutorial_audio_processor_graph.html which shows how to dynamically load AudioProcessor objects.
I would like to open their GUIs as they're loaded. This could be in separate windows or in the window that's got the slots for the graph.
I've tried creating a AudioProcessorEditor, but I'm at a loss on how to tell it to open.
Edit to add: What I've tried so far:
I've downloaded the code from the Tutorial: Cascading plug-in effects from https://docs.juce.com/master/tutorial_audio_processor_graph.html
I've also used ProJucer to create a new plugin. I've put the new plugin's files into the tutorial's files and used ProJucer to add PluginEditor.cpp and PluginEditor.h to the tutorial project.
I've changed the PluginEditor.h so the private class member audioProcessor is of type ProcessorBase&. And made ProcessorBase& the expected type for the data passed to the constructor.
In the tutorial code, in the header file, I've changed the ProcessorBase class so that the methods hasEditor() and createEditor() are just declarations and then modified main.cpp as follows:
#include "PluginEditor.h"
#include <iostream>
//=======================================================
juce::AudioProcessorEditor* ProcessorBase::createEditor()
{
std::cout "asking for an editor\n";
return new NewProjectAudioProcessorEditor (*this);
}
bool ProcessorBase::hasEditor() const
{ return true; }
In the included header, in the TutorialProcessor class, in the updateGraph() method, under the if (hasChanged), I've added slot->getProcessor()->createEditorIfNeeded (); on line 387-ish.
I can tell from my cout that createEditor() is being called and know that the constructor for the editor is running, but no window opens.
How do I tell it to open a window?
The code compiles and runs, but no window opens.