Question

I have seen somewhere this is 100% doable using blend behaviors, cannot find example.

Even better example would be to pass event args and/or sender as CommandParameter to specific command.

Answer 1

   <i:Interaction.Triggers>
        <i:EventTrigger EventName="SizeChanged">
            <ei:CallMethodAction MethodName="WndSizeChanged"
                TargetObject="{Binding}" />
        </i:EventTrigger>
    </i:Interaction.Triggers>

WndSizeChanged method should be public and have same signature as event delegte it subscribing to.