WPF 通过EventTrigger修改鼠标样式

<Button Content="this is button" x:Name="btn"     Height="150" Width="300"  >
            <Button.Triggers>
                <EventTrigger RoutedEvent="MouseMove">
                    <BeginStoryboard>
                        <Storyboard>
                            <ObjectAnimationUsingKeyFrames Duration="0:0:3" BeginTime="0:0:0" RepeatBehavior="Forever"  Storyboard.TargetProperty="Cursor">
                                <DiscreteObjectKeyFrame KeyTime="00:00:00">
                                    <DiscreteObjectKeyFrame.Value>
                                        <Cursor>Hand</Cursor>
                                    </DiscreteObjectKeyFrame.Value>
                                </DiscreteObjectKeyFrame>
                                <DiscreteObjectKeyFrame KeyTime="00:00:01">
                                    <DiscreteObjectKeyFrame.Value>
                                        <Cursor>Help</Cursor>
                                    </DiscreteObjectKeyFrame.Value>
                                </DiscreteObjectKeyFrame>
                                <DiscreteObjectKeyFrame KeyTime="00:00:02">
                                    <DiscreteObjectKeyFrame.Value>
                                        <Cursor>AppStarting</Cursor>
                                    </DiscreteObjectKeyFrame.Value>
                                </DiscreteObjectKeyFrame>
                            </ObjectAnimationUsingKeyFrames>
                        </Storyboard>
                    </BeginStoryboard>
                </EventTrigger>
            </Button.Triggers>
        </Button>