I have two CheckBoxes and a TextBox. I want to TextBox to have IsEnabled=False if both CheckBoxes have IsChecked=False. Can I do this with a MultiTrigger? I keep getting errors trying to use the Source property.

I have it working with MultiDataTriggers as you can see below. But have two questions.

1) Is this my only choice? Can I do it with a MultiTrigger?

<TextBox.Style>
    <Style TargetType="TextBox">
        <Style.Triggers>
            <MultiDataTrigger>
                <MultiDataTrigger.Conditions>
                    <Condition Binding="{Binding ElementName=uxDmm , Path=IsChecked}"
                                  Value="False" />
                    <Condition Binding="{Binding ElementName=uxGpm , Path=IsChecked}"
                                  Value="False" />
                </MultiDataTrigger.Conditions>
                <Setter Property="IsEnabled"
                          Value="False" />
            </MultiDataTrigger>
        </Style.Triggers>
    </Style>
</TextBox.Style>

2) Can I do this outside of the tag? I'm not really sure where Triggers can be applied, most samples do it within Style or DataTemplates, but defining it within a Style is messing up my default look and feel for the TextBox.