How can i dock a System.Windows.Controls.Data.DataGrid column to the right ?

hello, have datagrid stretches horizontally full width of page. defines 3 datagridtemplatecolumns . first datagridtemplatecolumn has fixed width, have third column dock right, , middle column stretched , fill remaining space. basically, need implement similar behaviour dockpanel. can advise me on how achieve this? thank you

ups - sorry

 

        <data:datagrid x:name="datagrid" sizechanged="datagrid_sizechanged">              <data:datagrid.columns>                  <data:datagridtextcolumn header="one" width="100"/>                  <data:datagridtextcolumn header="two"/>                  <data:datagridtextcolumn header="three" width="100"/>              </data:datagrid.columns>            </data:datagrid>  

  

 private void datagrid_sizechanged(object sender, sizechangedeventargs e)          {              double colomnsize = datagrid.actualwidth - (datagrid.columns[0].width.value + datagrid.columns[2].width.value);              datagrid.columns[1].width = new datagridlength(colomnsize);            }

 maybe have subtract 2 colomn seperators

Silverlight  >  Silverlight Controls and Silverlight Toolkit