如果您知道扩展器的内容,则可以使用 MultiDataTrigger 来执行此操作:
<Expander>
<Expander.Header>
<TextBlock>
<TextBlock.Style>
<Style TargetType="{x:Type TextBlock}">
<Setter Property="Text" Value="ERROR"/>
<Style.Triggers>
<MultiDataTrigger>
<MultiDataTrigger.Conditions>
<Condition Binding="{Binding ElementName=txtWidth, Path=(Validation.HasError)}" Value="False"/>
<Condition Binding="{Binding ElementName=txtHeight, Path=(Validation.HasError)}" Value="False"/>
</MultiDataTrigger.Conditions>
<Setter Property="Text" Value="NO ERROR"/>
</MultiDataTrigger>
</Style.Triggers>
</Style>
</TextBlock.Style>
</TextBlock>
</Expander.Header>
<StackPanel>
<TextBox x:Name="txtWidth" Text="{Binding Width, ElementName=rect, UpdateSourceTrigger=PropertyChanged, ValidatesOnExceptions=True}"/>
<TextBox x:Name="txtHeight" Text="{Binding Height, ElementName=rect, UpdateSourceTrigger=PropertyChanged, ValidatesOnExceptions=True}"/>
<Rectangle x:Name="rect" Width="100" Height="100" Margin="10" Fill="Green"/>
</StackPanel>
</Expander>
如果扩展器的内容未知,那么您可能必须在 TextBoxes 上设置 Binding.NotifyOnValidationError 并处理附加的错误事件。