如何使用相对位置设置textBox位置？

Question

In listbox contains multiple listitem, it will show first 5 record in listbox based on listbox height. If I scroll the listbox item 7th record or any in first position. if user scroll the listboxitem, I need to find out the listbox selected item which position is visible(with in 5 records displaying in listbox based on height)

Edit:

lstbxindex.ItemContainerGenerator.ContainerFromItem(lstbxindex.SelectedItem);

            System.Windows.Point relativePoint = lstbxindex.TransformToVisual(listBoxItem)
                               .Transform(new System.Windows.Point(0, 0));

Using this code I got the relative position of listbox selecteditem. if user scroll the listbox item after scroll need to overlay the textbox to the particular selected item position in listbox. So I check the condition like,

Listbox firstItem x=-2,y-2
Listbox secondItem x=-2,y=-56
Listbox thirdItem x=-2,y=-110
etc
relative position y increasing 54.

so I check

if(relativePoint.Y==56)
{
**//how to set the textbox to that relative position in listbox**
}

Answer 1

In winforms you could access the top visible item by using Listbox.TopIndex Property please check whether it is implemented in WPF !! below is the sample code in WINFORM App.

lstbxindex.Items[lstbxindex.TopIndex].ToString()