C# WPF ListBox Chat -

i'm working on c# wpf chat application. want skype chat, last added item touching bottom of listbox.

screenshot:

<listbox name="listboxmain" grid.column="1" grid.row="1">         <listbox.itemtemplate>             <datatemplate>                 <wrappanel>                     <textblock text="{binding user}" fontweight="bold" />                     <textblock text=": " fontweight="bold" />                     <textblock text="{binding text}" width="225" textwrapping="wrap" horizontalalignment="stretch" />                 </wrappanel>             </datatemplate>         </listbox.itemtemplate>     </listbox> 

you need update internal itemspaneltemplate of listbox... try this:

<listbox name="listboxmain" grid.column="1" grid.row="1">     <listbox.itemtemplate>         <datatemplate>             <wrappanel>                 <textblock text="{binding user}" fontweight="bold" />                 <textblock text=": " fontweight="bold" />                 <textblock text="{binding text}" width="225" textwrapping="wrap" horizontalalignment="stretch" />             </wrappanel>         </datatemplate>     </listbox.itemtemplate>     <listbox.itemspanel>         <itemspaneltemplate>             <stackpanel verticalalignment="bottom"/>         </itemspaneltemplate>     </listbox.itemspanel> </listbox>