动态修改Columndefinition宽度

您好，
我是一个WPF初学者...我想结合我的ViewModel的ColumnDefinition宽，Col0属性，这样当ContentControl的ContentControl的名称="NeedDataEntryControl"可见，Col0的GT;宽度= NeedDataEntryControl.width ...我如何实现这一目标时使用MVVM模式..
XAML是复制下面的..

<grid scrollviewer.verticalscrollbarvisibility="Disabled" name="allEntityGrid" scrollviewer.previewmousewheel="allEntity_PreviewMouseWheel">

        

        <grid.rowdefinitions>

            <rowdefinition height="*"></rowdefinition>

        </grid.rowdefinitions>

        <grid.columndefinitions>

            <columndefinition name="Col0" sharedsizegroup="shareThis" />

            <columndefinition name="ColSplitter" width="5"></columndefinition>

            <columndefinition name="Col2" width="*"></columndefinition>

        </grid.columndefinitions>

        <border borderthickness="1" borderbrush="#ACACAC">

        <scrollviewer name="NeedScrollViewer" verticalscrollbarvisibility="Auto" previewmousewheel="allEntity_PreviewMouseWheel">

            <grid name="needGrid" visibility="{Binding Path=HighLevelFilterMask, Converter={StaticResource HighLevelFilterMaskToVisibilityForNeed}}">

 

                <grid.rowdefinitions>

                    <rowdefinition height="Auto"></rowdefinition>

                    <rowdefinition height="*"></rowdefinition>

 

                </grid.rowdefinitions>

                    <contentcontrol name="NeedDataEntryControl" content="{Binding Path=NewNeedViewModel}" contenttemplate="{DynamicResource NeedDataEntryDataTemplate}">

                    <contentcontrol.style>

                        <Style TargetType="{x:Type ContentControl}">

                            <Style.Triggers>

                                    <datatrigger binding="{Binding Path=NewNeedViewModel.NeedDataEntryControlVisibility}" value="Collapsed">

                                    <setter property="Visibility" value="Collapsed" />

                                </datatrigger>

                                    <datatrigger binding="{Binding Path=NewNeedViewModel.NeedDataEntryControlVisibility}" value="Visible">

                                    <setter property="Visibility" value="Visible" />

                                </datatrigger>

                            </Style.Triggers>

                        </Style>

                    </contentcontrol.style>

                </contentcontrol>

 

                <local:careplanlistbox isincludedinglobalunselection="True" scrollviewer.horizontalscrollbarvisibility="Disabled" x:name="lstBoxAllNeeds" selectionmode="Single" xmlns:x="#unknown" xmlns:local="#unknown">

                  Grid.Row="1" Grid.Column="0"  HorizontalContentAlignment="Stretch"

                   ItemsSource="{Binding NeedsCollectionView}" ItemContainerStyle="{DynamicResource NeedCarePlanListBoxItem}"

                                        ItemTemplate="{DynamicResource NeedDataTemplateCompact}" AlternationCount="2" BorderThickness="0"></local:careplanlistbox>

 

            </grid>

        </scrollviewer>

        </border>

        <gridsplitter name="GridSplitter" dragincrement="{Binding }" resizebehavior="PreviousAndNext" removed="#FFFFFF" grid.row="0" grid.column="1" width="Auto" horizontalalignment="Stretch" verticalalignment="Stretch" resizedirection="Columns">

         

        </gridsplitter>

 



        <listbox isincludedinglobalunselection="True" scrollviewer.horizontalscrollbarvisibility="Disabled" x:name="lstBoxAllExecutions" selectionmode="Single" xmlns:x="#unknown">

               Grid.Row="0" Grid.Column="2"  HorizontalContentAlignment="Stretch"  ItemContainerStyle="{DynamicResource ExecutionCarePlanListBoxItem}"

               ItemTemplate="{DynamicResource ExecutionTemplate}"   ItemsSource="{Binding ExecutionsCollectionView}"

               AlternationCount="2" PreviewMouseWheel="lstAllExecutions_PreviewMouseWheel"

               Visibility="{Binding Path=HighLevelFilterMask, Converter={StaticResource HighLevelFilterMaskToVisibilityForExecution}}"  BorderBrush="#ACACAC" BorderThickness="1">

           

        </listbox>

 

        

 

    </grid>