c# - Excess spaces upon ribbon window -

i following tutorial here. here xaml code:

<window x:class="warm6.mainwindow"         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"         title="mainwindow" height="350" width="525">     <grid>         <grid.rowdefinitions>             <rowdefinition height="auto"/>             <rowdefinition height="*" />         </grid.rowdefinitions>          <ribbon x:name="ribbonwin">             <!-- icon on right side -->             <ribbon.helppanecontenttemplate>                 <datatemplate>                     <ribbonbutton smallimagesource="images\help.png" />                 </datatemplate>             </ribbon.helppanecontenttemplate>              <ribbon.applicationmenu>                 <ribbonapplicationmenu smallimagesource="images\window.png">                     <ribbonapplicationmenuitem header="open" tooltiptitle="application menu"                                                imagesource="images\window2.png"/>                     <ribbonapplicationmenuitem header="_save"                                                imagesource="images\save.png"/>                     <ribbonseparator/>                     <ribbonapplicationmenuitem header="_close" imagesource="images\close.png"/>                     <ribbonapplicationmenu.auxiliarypanecontent>                         <grid>                             <grid.rowdefinitions>                                 <rowdefinition height="auto" />                                 <rowdefinition height="5" />                                 <rowdefinition height="*" />                             </grid.rowdefinitions>                             <ribbonseparator grid.row="0" label="recently templates" />                         </grid>                     </ribbonapplicationmenu.auxiliarypanecontent>                 </ribbonapplicationmenu>             </ribbon.applicationmenu>              <ribbontab>              </ribbontab>         </ribbon>      </grid> </window> 

i find there space above ribbon window,like this:

please me improve it!

use ribbonwindow instead of window

<ribbonwindow x:class="warm6.mainwindow">      <!-- window content -->  </ribbonwindow>