Wpf 一个窗口中是否可能有多个不透明度？

我正在考虑做这样的事情：

<Grid> <-- opacity is .5
    <Grid></Grid> <-- opacity is .9 (of total opacity, not relative to parent)
    <Grid></Grid> <-- opacity is .9
    <Grid></Grid> <-- opacity is .9
</Grid>

---

这可能吗？

在另一个网格中管理网格

<Grid>
    <Grid.ColumnDefinitions>
        <ColumnDefinition/>
        <ColumnDefinition/>
        <ColumnDefinition/>
    </Grid.ColumnDefinitions>
    <Grid Grid.ColumnSpan="3"><Grid> <-- opacity is .5 
    <Grid Grid.Column="0"></Grid>    <-- opacity is .9
    <Grid Grid.Column="1"></Grid>    <-- opacity is .9 
    <Grid Grid.Column="2"></Grid>    <-- opacity is .9 
</Grid>