[4.8 P1] Slate SBox size problem

I changing some things in the engine but now i stuck in this part:

https://dl.dropboxusercontent.com/u/28070491/UE/Forums/TestA.png

In the justification line, cut the button and others next buttons are hide how change the size or how fix that ?

void FTextJustifyCustomization::CustomizeHeader(TSharedRef<IPropertyHandle> PropertyHandle, FDetailWidgetRow& HeaderRow, IPropertyTypeCustomizationUtils& CustomizationUtils)
{
	const FMargin OuterPadding(2); //2
	const FMargin ContentPadding(2); //2

	HeaderRow
	.NameContent()
	[
		PropertyHandle->CreatePropertyNameWidget()
	]
	.ValueContent()
	[
		SNew(SHorizontalBox)

		+ SHorizontalBox::Slot()
		.AutoWidth()
		.Padding(OuterPadding)
		[
			SNew( SCheckBox )
			.Style(FEditorStyle::Get(), "ToggleButtonCheckbox")
			.ToolTipText(LOCTEXT("HAlignTopLeft", "Align Text Top-Left"))
			.Padding(ContentPadding)
			.OnCheckStateChanged(this, &FTextJustifyCustomization::HandleCheckStateChanged, PropertyHandle, ETextJustify::TopLeft)
			.IsChecked(this, &FTextJustifyCustomization::GetCheckState, PropertyHandle, ETextJustify::TopLeft)
			[
				SNew(SImage)
				.Image(FEditorStyle::GetBrush("GridAlignment_TopLeft"))
			]
		]
 ...