Thanks for the tip. I found that changes to ActualHeight could be used as a trigger. I've tried to use an event trigger, and am currently stuck. Here's what I've done:
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="{Binding gridHeight}" />
</Grid.RowDefinitions>
<ListBox ItemsSource="{Binding PhotoList}" Grid.Row="0" >
<ListBox.Style>
<Style>
<Style.Triggers>
<EventTrigger RoutedEvent="SizeChanged">
<!-- Set {Binding tabHeight} to ActualHeight here -->
</EventTrigger>
</Style.Triggers>
</Style>
</ListBox.Style>
</ListBox>
</Grid>
The problem is, I can't figure out how to tell it to update tabHeight once the event is triggered. I initially thought I could use a Setter to update {Binding Path=tabHeight}. But that doesn't seem to be the case. Suggestions are much appreciated :)