Slate OnMouseLeave event triggered on mouse zero coordinates

Hi, the problem is that SCompoundWidget triggering OnMouseLeave event when mouse touches top or left sides of the viewport, but still in the viewport.

Please, help me fix that.

Here is a code of widget:

STest.h:

class CLOSETHEGATE_API STest : public SCompoundWidget
{
public:
	SLATE_BEGIN_ARGS(STest)
	{}
	SLATE_END_ARGS()

	void Construct(const FArguments& InArgs);
	virtual void OnMouseLeave(const FPointerEvent& MouseEvent) override;
};

STest.cpp:

void STest::Construct(const FArguments& InArgs)
{
    ChildSlot
	.VAlign(VAlign_Fill)
	.HAlign(HAlign_Fill)
	[
		CONTENT
	];
}
void STest::OnMouseLeave(const FPointerEvent& MouseEvent)
{
	UE_LOG(LogTemp, Error, TEXT("Out of widget"));
}

And somwhere in HUD created instance of the STest widget:

if (GEngine)
{
	GEngine->GameViewport->AddViewportWidgetContent
	(
		SNew(SWeakWidget)
		.PossiblyNullContent(STest_VARIABLE.ToSharedRef())
	);
}
STest_VARIABLE->SetVisibility(EVisibility::Visible);

So, with this code, when you touches left or top sides of window you will get “Out of widget” error in log.

Why u set .VAlign(VAlign_Fill).HAlign(HAlign_Fill) at childslot? Its fill by default.