Using VisualTreeHelper on listbox, can't get listboxitems

Question

I have the following XAML:

Answer 1

Please try this code snipped below to get the TextBox in ListBoxItem.

ListBox listbox = element as ListBox;
if (listbox != null && listbox.SelectedItem !=null)
{             
//find textbox and set focus here 

Textbox thisTextBox = (listbox.SelectedItem).Find("txt1") as Textbox;
if(thisTextBox !=null)
{
    thisTextBox.Focus();
    return;
}

}
int children = VisualTreeHelper.GetChildrenCount(element);         
for (int i = 0; i < children; i++)         
{
     DependencyObject child = VisualTreeHelper.GetChild(element, i);
     SetFocusOnTextBox(child);         
}