Easy example of How to create menus in the editor
Customizing the editor’s toolbar buttons menu via custom plugin

UE4 - Easy example of How to create menus in the editor
http://www.danielmayor.com/ue4-simple-menus

UE4 Level Editor
https://books.google.com.sg/books?id=zZ7cDgAAQBAJ&pg=PA272&lpg=PA272&dq=UE4+leveleditor+C%2B%2B&source=bl&ots=ZsX7ZCR6bV&sig=6_J7xzxTDosX5dOuLwpiaKrOSHU&hl=zh-CN&sa=X&ved=2ahUKEwji8aiT8orfAhWFTn0KHU0JB7wQ6AEwBXoECAUQAQ#v=onepage&q=UE4%20leveleditor%20C%2B%2B&f=false

Creating an Editor Module
https://wiki.unrealengine.com/Creating_an_Editor_Module

Customizing the editor’s toolbar buttons menu via custom plugin
https://answers.unrealengine.com/questions/25609/customizing-the-editors-toolbar-buttons-menu-via-c.html

UE4 Editor Toolbar Extention
https://blog.csdn.net/hui211314ddhui/article/details/79375548

Editor Event

Properties changed event

#if WITH_EDITOR
virtual void PostEditChangeProperty(FPropertyChangedEvent& PropertyChangedEvent) override;
#endif

Actor moved event

#if WITH_EDITOR
/** Called after an actor has been moved in the editor */
virtual void PostEditMove(bool bFinished);
#endif
How customize Transform of Actor in Editor

Header: Add VisibleAnywhere on properties.

UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = CameraEvent)
    UBoxComponent* BoxComp;

UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = CameraEvent)
    UArrowComponent* DirectionComp;

Constructor:

BoxComp = CreateDefaultSubobject<UBoxComponent>(TEXT("BoxComp"));
BoxComp->SetupAttachment(GetDefaultAttachComponent());

DirectionComp = CreateDefaultSubobject<UArrowComponent>(TEXT("TriggerDirectionComp"));
DirectionComp->SetupAttachment(BoxComp);

In Bluerpint Editor:

In Level Editor:

In Bluerpint Editor, you can’t modify Location and Rotation of RootComponent, but you can modify them in Level Editor.

How to spawn actor in Editor

example:

AActor* newActor = GEditor->AddActor(
    GEditor->LevelViewportClients[0]->GetWorld()->GetCurrentLevel(), AMyActorClass, MyTransform);
// modify properties on newActor
newActor->RerunConstructionScripts();

https://answers.unrealengine.com/questions/518445/actors-spawned-in-editor-do-not-run-their-construc.html

因为太爱一个人，所以不敢做真实的自己，反而越容易分手。