Setting focus on a ListBox item breaks keyboard navigation

StreamT picture StreamT · Feb 8, 2010 · Viewed 10.8k times · Source

After selecting ListBox item programmatically it is needed to press down\up key two times to move the selection. Any suggestions?

View:

<ListBox Name="lbActions" Canvas.Left="10" Canvas.Top="10"
               Width="260" Height="180">
        <ListBoxItem Name="Open" IsSelected="true" Content="Open"></ListBoxItem>
        <ListBoxItem Name="Enter" Content="Enter"></ListBoxItem>
        <ListBoxItem Name="Print" Content="Print"></ListBoxItem>
</ListBox>

Code:

public View()
{
   lbActions.Focus();
   lbActions.SelectedIndex = 0; //not helps
   ((ListBoxItem) lbActions.SelectedItem).Focus(); //not helps either
}

Answer

Heinzi picture Heinzi · Feb 8, 2010

Don't set the focus to the ListBox... set the focus to the selected ListBoxItem. This will solve the "two keyboard strokes required" problem:

if (lbActions.SelectedItem != null)
    ((ListBoxItem)lbActions.SelectedItem).Focus();
else
    lbActions.Focus();

If your ListBox contains something else than ListBoxItems, you can use lbActions.ItemContainerGenerator.ContainerFromIndex(lbActions.SelectedIndex) to get the automatically generated ListBoxItem.


If you want this to happen during window initialization, you need to put the code in the Loaded event rather than into the constructor. Example (XAML):

<Window ... Loaded="Window_Loaded">
    ...
</Window>

Code (based on the example in your question):

    private void Window_Loaded(object sender, RoutedEventArgs e)
    {
        lbActions.Focus();
        lbActions.SelectedIndex = 0;
        ((ListBoxItem)lbActions.SelectedItem).Focus();
    }