Question

I like to put separator line between items in ListBox control . With that separator line I want to make the ListBox look a like table with one column and many rows.

Answer 1

A basic approach would be to define a CSS style for the list box items:

<style type='text/css'>
option { border-top: solid 1px gray; }
</style>

...

<asp:ListBox ...></asp:ListBox>

This will add a gray border at the bottom of each listbox-element.

Note: this will apply to all listboxes on that page. If you need that style only for certain listboxes, then apply a CSS class to the listbox and change the CSS to apply only to those:

<style type='text/css'>
select.table option { border-top: solid 1px gray; }
</style>

...

<asp:ListBox CssClass="table" ...></asp:ListBox>