c# - how to get the height of multiline textbox increased automatically as form get stretched vertically in WPF -

i m using following hierarchy

 wpf form     - grid      - groupbox         - grid            -  multiline textbox 

can tell me how height of multiline textbox increased automatically form gets stretched vertically in wpf. form resizable user.

   <window x:class="wpfapp.userfunctions"         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"          xmlns:rp="clr-namespace:wpfapp"          windowstartuplocation="centerscreen"         resizemode="canresize"         title="user functions" showintaskbar="false"          minwidth="770" minheight="570" width="770" height="550"         icon="/wpfapp;component/images/globe.png"          name="frmuserfunctions" closing="onwindowclosing">         <grid margin="2" verticalalignment="stretch" height="auto">             <grid.resources>                 <resourcedictionary>                     <resourcedictionary.mergeddictionaries>                         <resourcedictionary source="../style/styledictionary.xaml"/>                     </resourcedictionary.mergeddictionaries>                 </resourcedictionary>             </grid.resources>             <grid.rowdefinitions>                 <rowdefinition height="auto" />                 <rowdefinition height="auto" minheight="40" />                 <rowdefinition height="auto" minheight="40" />                 <rowdefinition height="auto" minheight="40" />                 <rowdefinition height="auto" minheight="40" />                 <rowdefinition height="auto" minheight="40" />                 <rowdefinition height="auto" minheight="40" />                 <rowdefinition height="auto" minheight="40" />             </grid.rowdefinitions>             <label name="lblerrmsgdesp" foreground="red" fontweight="bold" visibility="collapsed"                      content="error"   margin="5,5,5,5" grid.row="0" ></label>              <groupbox name="grpcfl" margin="2" width="auto" verticalalignment="top" grid.row="1" grid.rowspan="2">                 <grid>                     <grid.rowdefinitions>                         <rowdefinition/>                         <rowdefinition/>                     </grid.rowdefinitions>                     <stackpanel orientation="vertical" margin="2" width="auto" grid.row="0" verticalalignment="top">                         <stackpanel margin="2" width="auto">                             <textblock name="tbcflstaticmessage" text=""                                        foreground="black"  margin="2" ></textblock>                         </stackpanel>                         <stackpanel orientation="horizontal" margin="2" width="auto">                             <button  name="btnopencfl" style="{dynamicresource btnmainnew}"                                                   click="onclickcflbrowse" margin="5" />                              <button  name="btnnewcfl" style="{dynamicresource btnmainnew}"                                                   click="onclicknewcfl" margin="5" />                              <button  name="btnsavecfl" style="{dynamicresource btnmainnew}"                                                  click="onclicksavecfl" margin="5" />                         </stackpanel>                     </stackpanel>                      <stackpanel orientation="vertical" margin="2" width="auto" grid.row="1"                                     verticalalignment="top">                         <textblock name="tbcflfilepath" foreground="black"  margin="2" ></textblock>                         <border borderthickness="1" borderbrush="lightgray" margin="2">                             <textblock minwidth="660"  isenabled="false" margin="1" name="tbcflfilename"                                         fontsize="13" foreground="black" minheight="20"/>                         </border>                     </stackpanel>                  </grid>             </groupbox>             <groupbox name="grpfunctions"  margin="2" verticalalignment="stretch" height="auto"                       horizontalalignment="stretch" grid.row="3" grid.rowspan="5">                 <grid  verticalalignment="stretch" height="auto">                     <grid.rowdefinitions>                         <rowdefinition/>                         <rowdefinition/>                         <rowdefinition/>                         <rowdefinition/>                         <rowdefinition/>                     </grid.rowdefinitions>                     <grid.columndefinitions>                         <columndefinition width="*"/>                     </grid.columndefinitions>                      <border borderthickness="0" borderbrush="lightgray" margin="2" grid.row="0">                         <grid margin="2" >                             <grid.columndefinitions>                                 <columndefinition width="auto"/>                                 <columndefinition width="auto"/>                             </grid.columndefinitions>                              <stackpanel orientation="horizontal" >                                 <button style="{dynamicresource btnmainnew}"                                   horizontalalignment="left" name="btnnew" margin="2,5,5,5" isenabled="false"                                 click="onclicknew"></button>                                 <button style="{dynamicresource btnmainnew}"                                  horizontalalignment="right" name="btnedit" margin="5,5,5,5"  isenabled="false"                                 click="onclickedit"></button>                                 <button style="{dynamicresource btnmainnew}"                                  horizontalalignment="right" name="btndelete" margin="5,5,5,5"  isenabled="false"                                 click="onclickdelete"></button>                             </stackpanel>                             <stackpanel grid.column="1" orientation="horizontal"                                  horizontalalignment="right" margin="2">                                  <button style="{dynamicresource btnmainnew}" content="clear"                                 horizontalalignment="right" name="btnreset" margin="5,5,5,5"                                  click="onclickreset"/>                                  <button style="{dynamicresource btnmainnew}" content="close" click="onclickclose"                                 horizontalalignment="right" name="btncancel" margin="5,5,5,5" />                             </stackpanel>                         </grid>                     </border>                      <stackpanel grid.row="1" margin="2" orientation="vertical" name="spselectfunction"                       width="auto"  verticalalignment="top">                         <textblock name="tbselectfunction" foreground="black" margin="5,2,2,2" width="auto"/>                         <combobox style="{dynamicresource cbobox}" isenabled="false" margin="5,2,2,2" maxwidth="1650"                           name="cmbfunctionslist" selectionchanged="onfunctionslistselectionchanged"                       verticalalignment="center"  minheight="25"  width="auto"/>                     </stackpanel>                      <stackpanel orientation="vertical" grid.row="1" name="spfunctionname"  margin="2"                          verticalalignment="top" visibility="collapsed">                         <textblock name="tbfunctionname" foreground="black"  width="auto"  margin="5,2,2,2"></textblock>                         <textbox  style="{dynamicresource txtbox}"  width="auto"                                  acceptsreturn="false" name="txtfunctionname" verticalalignment="center"                                   textchanged="onfunctionnametextchanged" margin="5,2,2,2" maxwidth="1650"                                  verticalscrollbarvisibility="auto" textwrapping="wrap"  />                     </stackpanel>                      <stackpanel grid.row="2"  margin="2" orientation="vertical" >                         <grid>                             <grid.columndefinitions>                                 <columndefinition  width="115"/>                                 <columndefinition  width="115"/>                                 <columndefinition  width="115"/>                                 <columndefinition  width="30"/>                                 <columndefinition  />                             </grid.columndefinitions>                             <grid.rowdefinitions>                                 <rowdefinition/>                                 <rowdefinition/>                                 <rowdefinition/>                             </grid.rowdefinitions>                              <textblock name="tbdatatypes" foreground="black"  grid.column="0" grid.row="0" margin="5,2,2,2" >                             </textblock>                             <textblock name="tboccurences" foreground="black"  grid.column="1" grid.row="0" margin="5,2,2,2">                             </textblock>                             <textblock name="tbparameterssize" foreground="black"  grid.column="2" grid.row="0" margin="5,2,2,2">                             </textblock>                             <textblock name="tbgeneratedsignaturelabel" foreground="black"  grid.row="0" grid.column="3" grid.columnspan="2" margin="5,2,2,2" />                             <combobox name="cmbdatatypes" grid.row="1" grid.column="0" margin="5"                                width="105" style="{dynamicresource cbobox}" itemssource="{binding}"                               selectionchanged="oncmbdatatypesselectionchanged" minheight="25"                                maxwidth="105" minwidth="105">                             </combobox>                              <combobox name="cmboccurences" grid.row="1" grid.column="1" margin="5"                                horizontalalignment="left" width="105" itemssource="{binding}"                               style="{dynamicresource cbobox}"                                minheight="25" maxwidth="105" minwidth="105"                               selectionchanged="oncmboccurencesselectionchanged">                             </combobox>                              <combobox name="cmbparametersno" grid.row="1" grid.column="2" margin="5"                                horizontalalignment="left" width="105" itemssource="{binding}"                               style="{dynamicresource cbobox}"                                minheight="25" maxwidth="105" minwidth="105"                               selectionchanged="oncmbparametersnoselectionchanged">                             </combobox>                             <textblock margin="0" name="tbgeneratedsignaturelocal" text="local:"  grid.row="1" grid.column="3"                                            foreground="black" textdecorations="none" verticalalignment="center" />                              <textblock margin="0" name="tbgeneratedsignature" grid.column="4" grid.row="1"                                            foreground="black" textdecorations="none" verticalalignment="center"/>                          </grid>                     </stackpanel>                      <stackpanel grid.row="3" name="grpdescription" orientation="vertical"  width="auto"                       verticalalignment="top"  margin="2">                         <textblock name="tbdescription" margin="5,2,2,2" foreground="black"></textblock>                         <textbox   style="{dynamicresource txtbox}" isenabled="false" margin="5,2,2,2"                       acceptsreturn="false" name="txtdescription" verticalalignment="center" maxwidth="1650"                       verticalscrollbarvisibility="auto" textwrapping="wrap" maxlines="1" isreadonly="false" />                     </stackpanel>                      <grid  grid.row="4" name="grpprogram" verticalalignment="stretch" margin="2"  minheight="120"                                  horizontalalignment="stretch" >                         <grid.rowdefinitions>                             <rowdefinition/>                             <rowdefinition height="auto"/>                         </grid.rowdefinitions>                          <grid.columndefinitions>                             <columndefinition width="*"/>                         </grid.columndefinitions>                          <textblock name="tbprogram" foreground="black" grid.row="0"  margin="5,2,2,2"  ></textblock>   <textbox grid.row="1" isenabled="false" margin="5,2,2,0"  acceptsreturn="true" name="txtprogram"                                  verticalalignment="stretch" width="auto"                           verticalscrollbarvisibility="auto" textwrapping="wrap" minheight="100" maxwidth="1650"  height="auto" />                      </grid>                  </grid>             </groupbox>         </grid>     </window> 

set horizontal , vertical alignment of textbox stretch. additionally have design grid - groupbox - grid, contains textbox, in such way increase height when size of window increases. can setting height of these controls equal * or alignment equal stretch (depending upon control). otherwise textbox won't increase it's height.