Question

I’m trying to bind to the ActualWidth of a column but the binding doesn’t seem to work. In the following example the TextBlock with the binding is always 0 yet the TextBlock updated via code reports the correct number. What’s happening?

XAML:

<Grid>
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="Auto" />
        <ColumnDefinition Width="*" Name="MainColumn" />
    </Grid.ColumnDefinitions>
    <StackPanel>
        <TextBlock Text="From Binding:" />
        <TextBlock Text="{Binding ElementName=MainColumn, Path=ActualWidth}" />
        <TextBlock Text="From Code:" />
        <TextBlock Text="" Name="WidthFromCodeTextBlock" />
    </StackPanel>
    <GridSplitter HorizontalAlignment="Right" Width="5" DragDelta="GridSplitter_DragDelta" />
</Grid>

Code:

private void GridSplitter_DragDelta(object sender, System.Windows.Controls.Primitives.DragDeltaEventArgs e)
{
    WidthFromCodeTextBlock.Text = MainColumn.ActualWidth.ToString();
}

Answer 1

Not a dependency property, hence no binding updates.

(Also, why do you have columns if you don’t use them?)