UGameUserSettings - RevertVideoMode not virtual

I have a class UKGameUserSettings deriving from UGameUserSettings.

In UGameUserSettings the function ConfirmVideoMode() is virtual.
I can therefore save my own attributes

void UKGameUserSettings::ConfirmVideoMode()
	LastUserConfirmedResolutionType = ResolutionType;

The problem is for the RevertVideoMode() which is not virtual.
Therefore, it is impossible to revert my own attributes like

void UKGameUserSettings::RevertVideoMode()
	ResolutionType = LastUserConfirmedResolutionType;

Definition of functions in UGameUserSettings:

class ENGINE_API UGameUserSettings : public UObject
	/** Mark current video mode settings (fullscreenmode/resolution) as being confirmed by the user */
	UFUNCTION(BlueprintCallable, Category=Settings)
	virtual void ConfirmVideoMode();

	/** Revert video mode (fullscreenmode/resolution) back to the last user confirmed values */
	UFUNCTION(BlueprintCallable, Category=Settings)
	void RevertVideoMode();