ToolTip可见性上的绑定错误

Question

我试图将ToolTip的可见性属性绑定到按钮的IsEnabled

 <Button Name="bbb" Content="Train" Command="{Binding TrainCmd}" ToolTipService.ShowOnDisabled="True">
      <Button.ToolTip>
          <ToolTip Content="{Binding TrainToolTip}" Visibility="{Binding IsEnabled, Converter={StaticResource InverseBooleanToVisibilityConverter}, ElementName=aaa}">
          </ToolTip>
      </Button.ToolTip>
 </Button> 

但我得到了以下错误：

"System.Windows.Data错误:4:无法找到与引用'ElementName=aaa‘绑定的源代码. BindingExpression:Path=IsEnabled；DataItem=null；目标元素是'ToolTip’(Name='')；目标属性是‘可见性’(类型‘可见性’)。“

我也试过

 <Button Content="Train" Command="{Binding TrainCmd}" ToolTipService.ShowOnDisabled="True">
    <Button.ToolTip>
        <ToolTip Content="{Binding TrainToolTip}" Visibility="{Binding IsEnabled, Converter={StaticResource InverseBooleanToVisibilityConverter}, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type Button}}}"/>
    </Button.ToolTip>
 </Button>

但后来我得到了

“AncestorType='System.Windows.Controls.Button'，错误:4:无法找到与引用'RelativeSource FindAncestor，RelativeSource AncestorLevel=‘1’. BindingExpression:Path=IsEnabled；DataItem=null；目标元素ToolTip‘(Name=’‘)绑定的源代码；目标属性为’可见性‘(键入’System.Windows.Data‘)。”

Answer 1

ToolTip不驻留在与PlacementTarget相同的可视树中。

 <Button Name="bbb" Content="Train" Command="{Binding TrainCmd}" ToolTipService.ShowOnDisabled="True">
      <Button.ToolTip>
           <ToolTip Content="{Binding TrainToolTip}" Visibility="{Binding PlacementTarget.IsEnabled, Converter={StaticResource InverseBooleanToVisibilityConverter}, RelativeSource={RelativeSource Self}">
            </ToolTip>
       </Button.ToolTip>
 </Button>