Is there a way to pass a parameter (or multiple params) to the CallMethodAction
behavior?
Try InvokeCommandAction a command instead of using CallMethodAction:
<i:Interaction.Triggers>
<i:EventTrigger EventName="TextChanged">
<i:InvokeCommandAction Command="{Binding TextChangedCommand}"
CommandParameter="{Binding ElementName=filterBox, Path=Text}"/>
</i:EventTrigger>
</i:Interaction.Triggers>
Hope it helps