FSlateBrush NormalBrush;

NormalBrush.DrawAs = ESlateBrushDrawType::RoundedBox;
NormalBrush.TintColor = FLinearColor(245 / 255.f, 245 / 255.f, 1.0f); //
NormalBrush.OutlineSettings.CornerRadii = FVector4(1.0f, 1.0f, 1.0f, 1.0f); // 圆角半径，分别对应4个角
NormalBrush.OutlineSettings.RoundingType = ESlateBrushRoundingType::FixedRadius;
NormalBrush.OutlineSettings.Color = FLinearColor(150 / 255.f, 150 / 255.f, 1.0f); //边框颜色
NormalBrush.OutlineSettings.Width = 3.0f;//边框宽度

UButton* button = WidgetTree->ConstructWidget<UButton>(UButton::StaticClass());

FButtonStyle MyButtonStyle;
MyButtonStyle.Normal = NormalBrush;
MyButtonStyle.Hovered = NormalBrush;
MyButtonStyle.Pressed = NormalBrush;

button->SetStyle(MyButtonStyle);