ToolTip is not fully visible

[SRKSHOME]

Hi, I have a textbox and which is having validation on its data. I am showing data error as a tooltip. But tooltip is not visible fully.how do i wrap it or increase its width?

<Setter Property="Validation.ErrorTemplate"
Value="{StaticResource ErrorTemplate}" />
<Style.Triggers>
<Trigger Property="Validation.HasError" Value="True">
<Setter Property="ToolTip">
<Setter.Value>
<Binding Path="(Validation.Errors)[0].ErrorContent" RelativeSource="{x:Static RelativeSource.Self}" />
</Setter.Value>
</Setter>
<Setter Property="BorderBrush" Value="#FF666666"/>
</Trigger>
</Style.Triggers>