How to get the reference pannel for a plugin getting scripted Slate

Development Programming & Scripting C++
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2 
			.WidthOverride(125.0f)
				[
					SNew(SClassPropertyEntryBox)
					.AllowNone(bAllowNone)
					.MetaClass(AGameModeBase::StaticClass())
					.SelectedClass(this, &FGameModeInfoCustomizer::GetCurrentGameModeClass)
					.OnSetClass(FOnSetClass::CreateSP(this, &FGameModeInfoCustomizer::SetCurrentGameModeClass))
				]

this seems to be it, but I need a reference to and actor something to not just a class …

Help!