How to do it...

1. Open your editor module's header file (Chapter_10Editor.h) and add the following code:

class FChapter_10EditorModule: public IModuleInterface 
{ 
    virtual void StartupModule() override;
    virtual void ShutdownModule() override;

    TArray< TSharedPtr<IAssetTypeActions> > CreatedAssetTypeActions;

    TSharedPtr<FExtender> ToolbarExtender;
    TSharedPtr<const FExtensionBase> Extension;

    IConsoleCommand* DisplayTestCommand;
    IConsoleCommand* DisplayUserSpecifiedWindow;

2. Add the following code within the implementation of StartupModule:

DisplayTestCommand = IConsoleManager::Get().RegisterConsoleCommand(TEXT("DisplayTestCommandWindow"), TEXT("test"), FConsoleCommandDelegate::CreateRaw(this, &FChapter_10EditorModule::DisplayWindow, FString(TEXT("Test Command Window"))), ECVF_Default);

    DisplayUserSpecifiedWindow = IConsoleManager::Get().RegisterConsoleCommand(TEXT("DisplayWindow"), TEXT("test"), FConsoleCommandWithArgsDelegate::CreateLambda(
        [&](const TArray< FString >& Args)
    {
        FString WindowTitle;
        for (FString Arg : Args)
        {
            WindowTitle += Arg;
            WindowTitle.AppendChar(' ');
        }
        this->DisplayWindow(WindowTitle);
    }

    ), ECVF_Default);

3. Inside ShutdownModule, add the following code:

if(DisplayTestCommand)
{
    IConsoleManager::Get().UnregisterConsoleObject(DisplayTestCommand);
    DisplayTestCommand = nullptr;
}

if(DisplayUserSpecifiedWindow)
{
    IConsoleManager::Get().UnregisterConsoleObject(DisplayUserSpecifiedWindow);
    DisplayUserSpecifiedWindow = nullptr;
}

4. Implement the following function in the editor module (Chapter_10Editor.h):

void DisplayWindow(FString WindowTitle) 
{ 
  TSharedRef<SWindow> CookbookWindow = SNew(SWindow) 
  .Title(FText::FromString(WindowTitle)) 
  .ClientSize(FVector2D(800, 400)) 
  .SupportsMaximize(false) 
  .SupportsMinimize(false); 
  IMainFrameModule& MainFrameModule = 
   FModuleManager::LoadModuleChecked<IMainFrameModule>
   (TEXT("MainFrame")); 
  if (MainFrameModule.GetParentWindow().IsValid()) 
  { 
    FSlateApplication::Get().AddWindowAsNativeChild
     (CookbookWindow, MainFrameModule.GetParentWindow()
     .ToSharedRef()); 
  } 
  else 
  { 
    FSlateApplication::Get().AddWindow(CookbookWindow); 
  } 
}

5. Compile your code and launch the editor.
6. Play the level, and then hit the tilde key to bring up the console.
7. Type DisplayTestCommandWindow and hit Enter:

8. You should see our tutorial window open up: