如何为网格背景而不是网格中的控件设置图像的不透明度动画？

只需分离该父子关系即可，这非常简单，因为您已经将其嵌入到Grid中了；

    <Window x:Class="george.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525" >
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition />
            <RowDefinition />
        </Grid.RowDefinitions>
        <Border>
            <Border.Style>
                <Style TargetType="Border">
                    <Setter Property="Background">
                        <Setter.Value>
                            <ImageBrush ImageSource="/George_mcfly.jpg" />
                        </Setter.Value>
                    </Setter>
                    <Setter Property="Opacity" Value="0.4" />
                    <Style.Triggers>
                        <EventTrigger RoutedEvent="Border.MouseEnter">
                            <BeginStoryboard>
                                <Storyboard>
                                    <DoubleAnimation To="0.8" AutoReverse="True" RepeatBehavior="Forever" Storyboard.TargetProperty="Opacity"></DoubleAnimation>
                                </Storyboard>
                            </BeginStoryboard>
                        </EventTrigger>
                        <EventTrigger RoutedEvent="Border.MouseLeave">
                            <BeginStoryboard>
                                <Storyboard>
                                    <DoubleAnimation To="0.3"  AutoReverse="True" RepeatBehavior="Forever" Storyboard.TargetProperty="Opacity"></DoubleAnimation>
                                </Storyboard>
                            </BeginStoryboard>
                        </EventTrigger>
                    </Style.Triggers>
                </Style>
            </Border.Style>
<!-- We end the Border so it's only behind the elements instead of acting as their parent -->
            </Border>
            <Grid Grid.Row="0">
                <Grid.RowDefinitions>
                    <RowDefinition Height="Auto"/>
                    <RowDefinition Height="Auto"/>
                    <RowDefinition Height="Auto"/>
                    <RowDefinition Height="Auto"/>
                    <RowDefinition Height="Auto"/>
                    <RowDefinition Height="60"/>
                    <RowDefinition Height="60"/>
                    <RowDefinition Height="Auto"/>
                    <RowDefinition Height="Auto" />
                </Grid.RowDefinitions>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition />
                    <ColumnDefinition />
                </Grid.ColumnDefinitions>
                <Label Content="{Binding ApplicationName}" FontSize="18" Grid.ColumnSpan="2" />
                <Label Content="Version:" Grid.Row="1" FontWeight="Bold" FontSize="14"/>
                <Label Content="{Binding Version}" FontSize="14" Foreground="Red" Grid.Row="1" Grid.Column="1"/>

                <Label Content="Current Connection:" Grid.Row="2" FontWeight="Bold"/>
                <Label Content="example" Grid.Row="2" Grid.Column="1"/>

                <ComboBox Grid.Row="3">
                    <ComboBoxItem Content="A" />
                    <ComboBoxItem Content="B" />
                </ComboBox>
                <Label Content="User Name: " Grid.Row="4" FontWeight="Bold"/>
                <Label Content="sample text" Grid.Row="4" Grid.Column="1"/>

                <Label Content="Active Directory Groups: " Grid.Row="5" FontWeight="Bold"/>
                <ListBox  Grid.Row="5" Grid.Column="1" Background="Transparent" BorderBrush="Transparent">
                    <ListBoxItem Content="1" />
                    <ListBoxItem Content="2" />
                    <ListBoxItem Content="3" />
                    <ListBoxItem Content="4" />
                </ListBox>
            </Grid>

    </Grid>

哦，McFly +1了，Marty和医生在哪里？:)

哦，而且，您可能会考虑将这些事件附加到父网格，并在动画中仅将边框定为目标，因为TargetName或TargetObject既然如此，则只有边框会定做。