Adding an Editor Actor Picker via Slate

[Shen_Yuju]

// in YourWindow.h
class xxx YourWindow : public SCompoundWidget
{

// other code...

FString ActorPath;
FString HandleActorPath() const {return ActorPath;}
void OnActorChanged(const FAssetData& InAsset) {ActorPath = InAsset.GetObjectPathString();}
}

// in YourWindow.cpp
SNew(SObjectPropertyEntryBox)
		.AllowedClass(AActor::StaticClass())
		.AllowClear(true)
		.DisplayBrowse(true)
		.DisplayUseSelected(true)
		.ObjectPath(this, &YourWindow::HandleActorPath)
		.OnObjectChanged(this, &YourWindow::OnActorChanged);