silverlight - How to full Screen popup in windows phone 8? -

hi; can not fit radmodalwindow on windows phone 8 application. how fill screen popup?

   <telerikprimitives:radmodalwindow name="cardselect" isfullscreen="true"                                           horizontalalignment="center" verticalalignment="center"                                           placementtarget="{binding elementname=contentpanel}"                                           isclosedonoutsidetap="true">                 <grid name="modalwindowgrid1"                       width="{binding programtdetailwidth, mode=twoway}"                        height="{binding programtdetailheight, mode=twoway}"                       horizontalalignment="center" verticalalignment="center">                     <grid.background>                         <imagebrush imagesource="assets/background.png"/>                     </grid.background>                      <grid.columndefinitions>                         <columndefinition width="*"/>                         <columndefinition width="*"/>                     </grid.columndefinitions>                     <grid.rowdefinitions>                         <rowdefinition height="auto" />                         <rowdefinition height="auto" />                      </grid.rowdefinitions>                     <border borderbrush="#ff0a0611" borderthickness="0" grid.row="2">                         <border.background>                             <lineargradientbrush endpoint="0.5,1" startpoint="0.5,0">                                 <gradientstop color="#ff45374d"/>                                 <gradientstop color="#ff1e092a" offset="1"/>                             </lineargradientbrush>                         </border.background>                         <border borderthickness="3" horizontalalignment="left" width="330" height="392" verticalalignment="top">                             <border.borderbrush>                                 <solidcolorbrush color="#fff2f1f3"/>                             </border.borderbrush>                             <stackpanel horizontalalignment="center" width="330" margin="-3,0" >                                 <stackpanel x:name="mainpanel" height="385">                                     <border borderthickness="0,0,0,3" height="70" verticalalignment="top" margin="0,0,1,0">                                         <border.borderbrush>                                             <solidcolorbrush color="#fff2f1f3"/>                                         </border.borderbrush>                                         <textblock horizontalalignment="center" margin="0,22,0,15" textwrapping="wrap" verticalalignment="center" fontsize="21.333" height="32" width="209" grid.rowspan="2" text="dijital kart no seçiniz"/>                                     </border>                                     <stackpanel x:name="waitingpanel" margin="0,60" horizontalalignment="center" visibility="collapsed">                                         <textblock text="kayıt işlemi sürüyor." verticalalignment="center" fontsize="21.333" horizontalalignment="center"/>                                         <progressbar x:name="pgb" width="250" isindeterminate="true" margin="0,10                              ,0,0" value="0"  />                                     </stackpanel>                                     <grid x:name="grdclient" horizontalalignment="left" verticalalignment="top" height="313" width="329">                                         <grid.rowdefinitions>                                             <rowdefinition height="255*"/>                                             <rowdefinition height="58*"/>                                         </grid.rowdefinitions>                                          <button x:name="btnok" content="ok" horizontalalignment="right" height="46" margin="0,0,21,0" verticalalignment="center" width="119" click="btnrecord_click" grid.row="1"/>                                         <button x:name="btncancel" content="vazgeç" horizontalalignment="left" height="46" margin="21,0,0,0" verticalalignment="center" width="119" click="btncancel_click_1" grid.row="1"/>                                         <listbox name="lstcards" selectionmode="single" horizontalalignment="left" height="210" margin="21,21,0,0" verticalalignment="top" width="287"  itemssource="{binding}"></listbox>                                      </grid>                                   </stackpanel>                             </stackpanel>                         </border>                     </border>                 </grid>             </telerikprimitives:radmodalwindow> 

it looks window's content not big enough fill screen. radmodalwindow fill whole screen, area not covered content show behind via transparency.

make main grid auto size fill screen. alternately, setting background colour or image on window should ensure transparency doesn't show content behind window.