USTRUCT(BlueprintType)
struct TESTGRAPH_API FCustomDetailStruct
{
	GENERATED_USTRUCT_BODY()

	UPROPERTY(EditInstanceOnly, BlueprintReadWrite)
	FName SelectedName;

};

class FCustomDetailStructView : public IPropertyTypeCustomization
{
public:
	/** Makes a new instance of this detail layout class for a specific detail view requesting it */
	static TSharedRef<IPropertyTypeCustomization> MakeInstance();
	/** IPropertyTypeCustomization interface */
	virtual void CustomizeHeader( TSharedRef<class IPropertyHandle> StructPropertyHandle, class FDetailWidgetRow& HeaderRow, IPropertyTypeCustomizationUtils& StructCustomizationUtils ) override;
	virtual void CustomizeChildren( TSharedRef<class IPropertyHandle> StructPropertyHandle, class IDetailChildrenBuilder& StructBuilder, IPropertyTypeCustomizationUtils& StructCustomizationUtils ) override;
private:
 	...
};

void FCustomDetailStructView::CustomizeHeader( TSharedRef<class IPropertyHandle> StructPropertyHandle, class FDetailWidgetRow& HeaderRow, IPropertyTypeCustomizationUtils& StructCustomizationUtils )
{
	MyStructProperty = StructPropertyHandle;
	PropUtils = StructCustomizationUtils.GetPropertyUtilities().Get();

	MyKeyNameProperty = MyStructProperty->GetChildHandle(TEXT("SelectedName"));
	KeyValues.Reset();
	KeyValues.Add(TEXT("John"));
	KeyValues.Add(TEXT("Amy"));
	KeyValues.Add(TEXT("Peter"));

	HeaderRow.IsEnabled(TAttribute<bool>::Create(TAttribute<bool>::FGetter::CreateSP(this, &FCustomDetailStructView::IsEditingEnabled)))
		.NameContent()
		[
			StructPropertyHandle->CreatePropertyNameWidget()
		]
		.ValueContent()
		[
			SNew(SComboButton)
			.OnGetMenuContent(this, &FCustomDetailStructView::OnGetKeyContent)
 			.ContentPadding(FMargin( 2.0f, 2.0f ))
			.IsEnabled(this, &FCustomDetailStructView::IsEditingEnabled)
			.ButtonContent()
			[
				SNew(STextBlock) 
				.Text(this, &FCustomDetailStructView::GetCurrentKeyDesc)
				.Font(IDetailLayoutBuilder::GetDetailFont())
			]
		];

	MyKeyNameProperty->SetValue(KeyValues[0]);
}

TSharedRef<SWidget> FCustomDetailStructView::OnGetKeyContent() const
{
	FMenuBuilder MenuBuilder(true, NULL);

	for (int32 Idx = 0; Idx < KeyValues.Num(); Idx++)
	{
		FUIAction ItemAction( FExecuteAction::CreateSP( this, &FCustomDetailStructView::OnKeyComboChange, Idx) );
		MenuBuilder.AddMenuEntry( FText::FromName( KeyValues[Idx] ), TAttribute<FText>(), FSlateIcon(), ItemAction);
	}

	return MenuBuilder.MakeWidget();
}

void FXXX_EditorModule::StartupModule()
{
	....
	// Register the details customizer
	FPropertyEditorModule& PropertyModule = FModuleManager::LoadModuleChecked<FPropertyEditorModule>("PropertyEditor");
	PropertyModule.RegisterCustomPropertyTypeLayout("CustomDetailStruct", FOnGetPropertyTypeCustomizationInstance::CreateStatic(&FCustomDetailStructView::MakeInstance));
	PropertyModule.NotifyCustomizationModuleChanged();
}