xaml - Grid column definitions -

inside same stackpanel i'd put control aligned on left , 1 on right side. made attempt using grid , defining columndefinitions no luck.

<stackpanel orientation="horizontal">                     <grid>                         <grid.columndefinitions>                             <columndefinition width="auto" />                             <columndefinition width="72" />                         </grid.columndefinitions>                          <stackpanel horizontalalignment="left" grid.column="0" orientation="horizontal">                              <button />                         </stackpanel>                          <stackpanel horizontalalignment="right" grid.column="1">                             <button height="72" width="72" />                              </stackpanel>                     </grid>                 </stackpanel> 

the first column take 50% 80% of total width (depending on content), while second column take 72px. how can set first column fills total grid width minus 72px?

set width property of first column star:

    <columndefinition width="*" /> 

making change in code should work:

<stackpanel>     <grid>         <grid.columndefinitions>             <columndefinition width="*" />             <columndefinition width="72" />         </grid.columndefinitions>          <stackpanel grid.column="0" orientation="horizontal">             <button />         </stackpanel>          <stackpanel horizontalalignment="right" grid.column="1">             <button height="72" width="72" />         </stackpanel>     </grid> </stackpanel>