使用ScrollViewer时，发现如果包含在Grid里，可以显示出滚动条；

但是放到StackPanel里，为什么就显示不了？

1.放在StackPanel中

<StackPanel>
<ScrollViewer Margin="0" VerticalScrollBarVisibility="Auto">
<StackPanel Margin="0">
<Button Content="Button" />
<Button Content="Button" />
<Button Content="Button" />
<Button Content="Button" />
<Button Content="Button" />
<Button Content="Button" />
<Button Content="Button" />
<Button Content="Button" />
<Button Content="Button" />
<Button Content="Button" />
<Button Content="Button" />
<Button Content="Button" />
<Button Content="Button" />
<Button Content="Button" />
<Button Content="Button" />
</StackPanel>
</ScrollViewer>
</StackPanel>

2.放在Grid中

<Grid>
<ScrollViewer Margin="0" VerticalScrollBarVisibility="Auto">
<StackPanel Margin="0">
<Button Content="Button" />
<Button Content="Button" />
<Button Content="Button" />
<Button Content="Button" />
<Button Content="Button" />
<Button Content="Button" />
<Button Content="Button" />
<Button Content="Button" />
<Button Content="Button" />
<Button Content="Button" />
<Button Content="Button" />
<Button Content="Button" />
<Button Content="Button" />
<Button Content="Button" />
<Button Content="Button" />
</StackPanel>
</ScrollViewer>
</Grid>