Initiating a method on a control in the child viewmodel from the root viewmodel

[jgarner07]

Forgive me if I do not have the correct terminology. I have only been programming for a couple years.

When studying MVVM at first really just seemed like an infinitely complex way to restrain the capability of your application. Like a Rube Goldberg machine designed to cut my wobbly green c# programming sea legs out from under me.

Part of my difficulty was that I am working on an application that isnt quite your standard application connected to a database doing CRUD operations.

But after reading through Stylet Wiki and learning the viewmodel first approach seems much much simpler and makes TOTAL SENSE!....so an immense thank you to the people working on this project! I love it!!!!

With that out of the way, I have a small application that can display a host of different file types (html, pdf, tiff, txt, has a web browser etc...). What is displayed is determined by command line parameters passed to it on launch. In my root viewmodel I have a traditional menu system (file, edit help) and some buttons (Print, Save, Copy) along a top bar.

The production version (non MVVM) of this application has 6 code behind pages each with a dozen click events all performing the same actions. When I change something, I gotta go change it in 6 or more places.

With the awesomeness of Stylet, I can consolidate the actions of these controls into one place and reuse that code then pass in the viewing area (text file viewer control, pdf file viewer control, browser control etc..) into a user control as a child viewmodel!

Well, almost. My edit menu has "select all" and "copy". Actions which are to be performed on the specific control in the child viewmodel. I can Bind these menu choices to the ActiveItem (Active child viewmodel) but how would I command say the Telerik RadPdfViewer to use it's "selectall" extension method from a menu item all the way back up into the root viewmodel?

If an action is initiated from the view side with an event, you can grab the object sender and cast it into whatever I want and do something with it. But initiating something like "select all" text from the viewmodel side there is no handle I can grab to tell the control to do something. Below is my code.

Root View

<Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="1*"/>
            <ColumnDefinition Width="1*"/>
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition Height="20"/>
            <RowDefinition Height="70"/>
            <RowDefinition Height="9*"/>
        </Grid.RowDefinitions>
        
        <!--Menu Bar-->
        <Menu x:Name="Menu" Grid.Row="0" FontSize="14" 
              FontFamily="arial" Background="DarkGray" 
              HorizontalAlignment="Stretch" VerticalAlignment="Stretch" 
              Width="auto" Height="auto" 
              Grid.ColumnSpan="2" Margin="0,0,0,1"
              GotMouseCapture="{s:Action CanExecuteCopyText}">

            <MenuItem Header="File">
                <MenuItem x:Name="mnuPrint" Header="Print" 
                          InputGestureText="Ctrl+P"
                          Command="{s:Action Print}"/>
                
                <MenuItem x:Name="mnuSave" Header="Save" 
                          InputGestureText="Ctrl+S" 
                           Command="{s:Action Save}"/>
                
                <MenuItem x:Name="mnuExit" Header="Exit" 
                          InputGestureText="Ctrl+Q" 
                           Command="{s:Action Close}"/>
            </MenuItem>

            <MenuItem Header="Edit" >

                <MenuItem x:Name="mnuSelAll" Header="Select All" 
                          InputGestureText="Ctrl+A" 
                          s:View.ActionTarget="{Binding ActiveItem}"
                          Command="{s:Action SelectAll}" />
                
                <MenuItem x:Name="mnuCopy" Header="Copy" 
                          InputGestureText="Ctrl+C"
                          IsEnabled="{Binding CopyTextIsEnabled, UpdateSourceTrigger=PropertyChanged}"
                          Command="{s:Action CopyText}" />
            </MenuItem>
            
            <MenuItem x:Name="mnuHelp" Header="Help">
                <MenuItem x:Name="mnuAbout" Header="About" 
                          Command="{s:Action About}" />
            </MenuItem>
        </Menu>
        
        <!--Header Control -->
        <Border HorizontalAlignment="Stretch" Height="auto" Grid.Row="1" 
                VerticalAlignment="Stretch" Width="auto" Background="LightGray" 
                Grid.ColumnSpan="2">
            <Grid>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="*"/>
                    <ColumnDefinition Width="3*"/>
                    <ColumnDefinition Width="*"/>
                </Grid.ColumnDefinitions>
                
                <ToolBarPanel VerticalAlignment="Center" HorizontalAlignment="Left" 
                              Orientation="Horizontal" Margin="10,0,0,0" >

                    <telerik:RadButton x:Name="btnPrint" Content="Print" 
                                       Command="{s:Action Print}"
                                       Height="30" Width="50" 
                                       Margin="3,0,0,0" 
                                       Style="{DynamicResource RadButtonStyle}" />
                    
                    <telerik:RadButton x:Name="btnCopy" Content="Copy"
                                       Command="{s:Action CopyFile}"
                                       Height="30" Width="50" Margin="3,0,0,0" 
                                       Style="{DynamicResource RadButtonStyle}" />
                    
                    <telerik:RadButton x:Name="btnSave" Content="Save" 
                                       Command="{s:Action Save}"
                                       Height="30" Width="50" Margin="3,0,0,0" 
                                       Style="{DynamicResource RadButtonStyle}" />
                </ToolBarPanel>
                
                <StackPanel x:Name="pnlCenter" Grid.Row="1" Grid.Column="1" 
                            Orientation="Vertical" Width="auto" Height="auto"
                            HorizontalAlignment="Stretch" VerticalAlignment="Stretch"  >
                    
                    <TextBlock x:Name="tblAddress" TextWrapping="Wrap" Foreground="Gray" 
                               TextAlignment="Center" 
                               HorizontalAlignment="Stretch" VerticalAlignment="Top" 
                               Height="20" Width="auto"/>
                </StackPanel>
                
                <DockPanel x:Name="pnlRightButtons" Grid.Column="2" 
                           HorizontalAlignment="Stretch" VerticalAlignment="Stretch" 
                           Width="auto" Height="auto">
                    
                    <TextBlock Text="EST Viewer" FontSize="28" FontWeight="Bold" 
                               Foreground="Navy" Height="40" Width="auto" 
                               HorizontalAlignment="Center" VerticalAlignment="Center" />
                </DockPanel>
            </Grid>
        </Border>

        <!--User Control Swapping in Viewing surface depending on content-->
        <UserControl x:Name="usrControl"
                     Grid.Row="3" Grid.ColumnSpan="2"
                     s:View.Model="{Binding ActiveItem}" >
        </UserControl>
    </Grid>

Root ViewModel

using ESTClient.HelperClasses;
using ESTClient.Models;
using Stylet;
using System;
using System.Collections.Generic;
using System.Text;
using System.Windows;
using Telerik.Windows.Automation.FixedDocumentViewer;
using Telerik.Windows.Controls;
using Telerik.Windows.Documents.Commands;
using Telerik.Windows.Documents.Commands.Descriptors;
using Telerik.Windows.Documents.Fixed.Model;
using Telerik.Windows.Documents.Fixed.Text;

namespace ESTClient.ViewModels
{
   public class RootViewModel : Conductor<object>
    {
        private MyApplication MyApplication = new MyApplication();
        private readonly IWindowManager _windowManager;
        public PDFViewModel PDFViewModel { get; private set; }

        private bool _copyTextIsEnabled;
        public bool CopyTextIsEnabled
        {
            get
            {
                return _copyTextIsEnabled; // !String.IsNullOrEmpty(PDFViewModel.HighlightedText);
            }
            set
            {
                SetAndNotify(ref _copyTextIsEnabled, value);
            }

        }

        #region Methods

        public RootViewModel(IWindowManager windowManager)
        {
            _windowManager = windowManager;

            //Processing command line arguments and storing session settings in the MyApplicaiton object
            string[] args = Environment.GetCommandLineArgs();
            CommandLineArgs commandLineArgs = new CommandLineArgs();
            MyApplication = commandLineArgs.Process_Args(args);

            PDFViewModel = new PDFViewModel(MyApplication);

            //Loading Viewer
            Load_ChildViewModel(MyApplication);

        }

        public void Load_ChildViewModel(MyApplication myApplication)
        {
            switch (myApplication.ViewerType)
            {
                case "pdf":
                    ActivateItem(PDFViewModel);
                    return;
                case "txt":
                    return;
            }
        }

        /// <summary>
        /// Prints the file
        /// </summary>
        public void Print()
        {
            switch (MyApplication.ViewerType)
            {
                case "pdf":

                    PrintDoc printDoc = new PrintDoc(MyApplication);
                    printDoc.Print_PDFAsync();
                    return;

                case "txt":

                    return;
            }
        }
        
        /// <summary>
        /// Saves the file by launching the SaveViewModel
        /// </summary>
        public void Save()
        {
            _windowManager.ShowWindow(new SaveViewModel(MyApplication, _windowManager));
        }
        
        /// <summary>
        /// Copies file to clipboard
        /// </summary>
        public void CopyFile()
        {
            System.Collections.Specialized.StringCollection data = new System.Collections.Specialized.StringCollection();
            data.Add(MyApplication.ArgsUrl);
            Clipboard.SetFileDropList(data);
        }

        public void CopyText()
        {
            switch (MyApplication.ViewerType)
            {
                case "pdf":
                    Clipboard.SetText(PDFViewModel.HighlightedText);
                    return;
                case "txt":
                    return;
            }
        }

        public void About()
        {
            _windowManager.ShowMessageBox("EST Client Version " + System.Reflection.Assembly.GetExecutingAssembly());
        }

        public void Close()
        {
            App.Current.Shutdown();
        }

        public void CanExecuteCopyText()
        {
            
            if (String.IsNullOrEmpty(PDFViewModel.HighlightedText))
            {
                CopyTextIsEnabled = false;
            }
            else
            {
                CopyTextIsEnabled = true;
            }

        }

        

        #endregion

        #region Events



        #endregion
    }
}

Child View

<UserControl x:Class="ESTClient.Views.PDFView"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:converters="clr-namespace:Telerik.Windows.Documents.Converters;assembly=Telerik.Windows.Controls.FixedDocumentViewers"
             xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation"
             xmlns:s="https://github.com/canton7/Stylet"
             xmlns:local="clr-namespace:ESTClient.Views" 
             mc:Ignorable="d" 
             d:DesignHeight="450" d:DesignWidth="800" 
             FocusManager.FocusedElement="{Binding ElementName=radPdfViewer}" >
    <UserControl.Resources>
        <converters:FixedDocumentViewerModeConverter x:Key="ModeConverter" />
        <converters:BoolToVisibilityConverter x:Key="BoolToVisibilityConverter" />
        <telerik:InvertedBooleanConverter x:Key="InvertedBooleanConverter"/>
    </UserControl.Resources>
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="30" />
            <RowDefinition Height="20*"/>
        </Grid.RowDefinitions>

        <!--PDF ToolBar-->
        <telerik:RadToolBar x:Name="tbrPDF" 
                            DataContext="{Binding ElementName=radPdfViewer, Path=CommandDescriptors}" 
                            Grid.Row="0" VerticalAlignment="Top" Height="30" Margin="0" Width="auto" 
                            telerik:StyleManager.Theme="Office_Black">
            
            <telerik:RadButton x:Name="counterClockwiseButton" 
                               Command="{Binding RotateCounterClockwiseCommandDescriptor.Command}" 
                               Padding="0" IsBackgroundVisible="False" HorizontalAlignment="Left" 
                               VerticalAlignment="Stretch">
                <ToolTipService.ToolTip>
                    <TextBlock Text="Rotate counterclockwise" />
                </ToolTipService.ToolTip>
                <TextBlock Padding="4 0" FontFamily="{StaticResource TelerikWebUILocal}" FontSize="16"
                           Text="{StaticResource GlyphReset}"
                           Foreground="{Binding RelativeSource={RelativeSource AncestorType=ContentPresenter}, Path=(TextElement.Foreground)}" 
                           IsEnabled="False" />
            </telerik:RadButton>
            
            <telerik:RadButton x:Name="clockwiseButton" 
                               Command="{Binding RotateClockwiseCommandDescriptor.Command}"                                    
                               Padding="0" IsBackgroundVisible="False" HorizontalAlignment="Left" 
                               VerticalAlignment="Stretch">
                <ToolTipService.ToolTip>
                    <TextBlock Text="Rotate clockwise" />
                </ToolTipService.ToolTip>
                <TextBlock Padding="4 0" FontFamily="{StaticResource TelerikWebUILocal}" FontSize="16"
                           Text="{StaticResource GlyphReload}"
                           Foreground="{Binding RelativeSource={RelativeSource AncestorType=ContentPresenter}, Path=(TextElement.Foreground)}" />
            </telerik:RadButton>
            
            <telerik:RadToolBarSeparator/>
            
            <telerik:RadButton Command="{Binding PageUpCommandDescriptor.Command}" 
                               Visibility="{Binding PageUpCommandDescriptor.IsEnabled, Converter={StaticResource BoolToVisibilityConverter}}"  
                               HorizontalAlignment="Left" VerticalAlignment="Stretch" Padding="0" 
                               HorizontalContentAlignment="Center" VerticalContentAlignment="Center" 
                               IsBackgroundVisible="False">
                <ToolTipService.ToolTip>
                    <TextBlock Text="Previous page" />
                </ToolTipService.ToolTip>
                <TextBlock Padding="4 0" FontFamily="{StaticResource TelerikWebUILocal}" FontSize="16"
                           Text="{StaticResource GlyphArrowUp}"
                           Foreground="{Binding RelativeSource={RelativeSource AncestorType=ContentPresenter}, Path=(TextElement.Foreground)}" />
            </telerik:RadButton>
            
            <telerik:RadButton Command="{Binding PageDownCommandDescriptor.Command}" 
                               Visibility="{Binding PageDownCommandDescriptor.IsEnabled, Converter={StaticResource BoolToVisibilityConverter}}" 
                               HorizontalAlignment="Left" VerticalAlignment="Stretch" Padding="0" 
                               HorizontalContentAlignment="Center" VerticalContentAlignment="Center" 
                               IsBackgroundVisible="False">
                <ToolTipService.ToolTip>
                    <TextBlock Text="Next page" />
                </ToolTipService.ToolTip>
                <TextBlock Padding="4 0" FontFamily="{StaticResource TelerikWebUILocal}" FontSize="16"
                           Text="{StaticResource GlyphArrowDown}"
                           Foreground="{Binding RelativeSource={RelativeSource AncestorType=ContentPresenter}, Path=(TextElement.Foreground)}" />
            </telerik:RadButton>

            <TextBox x:Name="tbCurrentPage" Width="30" Margin="2 1" 
                     Text="{Binding FixedDocumentViewer.CurrentPageNumber, Mode=TwoWay}" 
                     HorizontalContentAlignment="Center" />
            
            <TextBlock VerticalAlignment="Center" Margin="2 1" Text="/" />
            
            <TextBlock VerticalAlignment="Center" Margin="2 1 3 1" 
                       Text="{Binding FixedDocumentViewer.PagesCount}" />
            
            <telerik:RadToolBarSeparator/>

            <telerik:RadButton Command="{Binding ZoomInCommandDescriptor.Command}" 
                               Visibility="{Binding ZoomInCommandDescriptor.IsEnabled, Converter={StaticResource BoolToVisibilityConverter}}" 
                               HorizontalAlignment="Left" VerticalAlignment="Stretch" Padding="0" 
                               HorizontalContentAlignment="Center" VerticalContentAlignment="Center" 
                               IsBackgroundVisible="False">
                <ToolTipService.ToolTip>
                    <TextBlock Text="Zoom in" />
                </ToolTipService.ToolTip>
                <TextBlock Padding="4 0" FontFamily="{StaticResource TelerikWebUILocal}" FontSize="16"
                           Text="{StaticResource GlyphZoomIn}"
                           Foreground="{Binding RelativeSource={RelativeSource AncestorType=ContentPresenter}, Path=(TextElement.Foreground)}" />
            </telerik:RadButton>
            
            <telerik:RadButton x:Name="PART_btnZoomOut" 
                               Command="{Binding ZoomOutCommandDescriptor.Command}" 
                               Visibility="{Binding ZoomOutCommandDescriptor.IsEnabled, Converter={StaticResource BoolToVisibilityConverter}}" 
                               HorizontalAlignment="Left" VerticalAlignment="Stretch" Padding="0" 
                               HorizontalContentAlignment="Center" VerticalContentAlignment="Center" 
                               IsBackgroundVisible="False">
                <ToolTipService.ToolTip>
                    <TextBlock Text="Zoom out" />
                </ToolTipService.ToolTip>
                <TextBlock Padding="4 0" FontFamily="{StaticResource TelerikWebUILocal}" FontSize="16"
                           Text="{StaticResource GlyphZoomOut}"
                           Foreground="{Binding RelativeSource={RelativeSource AncestorType=ContentPresenter}, Path=(TextElement.Foreground)}" />
            </telerik:RadButton>
            
            <telerik:PercentComboBox Value="{Binding ElementName=radPdfViewer, Path=ScaleFactor, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" 
                                     RadPdfViewer="{Binding ElementName=radPdfViewer}" 
                                     MaxHeight="26">
                <telerik:PercentComboBox.PercentValues>
                    <telerik:Percent Value="10"/>
                    <telerik:Percent Value="25"/>
                    <telerik:Percent Value="50"/>
                    <telerik:Percent Value="75"/>
                    <telerik:Percent Value="100"/>
                    <telerik:Percent Value="150"/>
                    <telerik:Percent Value="200"/>
                    <telerik:Percent Value="500"/>
                    <telerik:Percent Value="1000"/>
                    <telerik:Percent Value="2000"/>
                </telerik:PercentComboBox.PercentValues>
            </telerik:PercentComboBox>
            
            <telerik:RadToolBarSeparator />
            
            <telerik:RadToggleButton x:Name="fitToWidthButton"
                                     Command="{Binding FitToWidthFixedDocumentPagesPresenterCommandDescriptor.Command}" 
                                     IsEnabled="{Binding FitToWidthFixedDocumentPagesPresenterCommandDescriptor.IsEnabled, Converter={StaticResource InvertedBooleanConverter}, Mode=TwoWay}" 
                                     IsChecked="{Binding FitToWidthFixedDocumentPagesPresenterCommandDescriptor.IsEnabled, Mode=TwoWay}"
                                     Padding="0" IsBackgroundVisible="False" HorizontalAlignment="Left" 
                                     VerticalAlignment="Stretch">
                <ToolTipService.ToolTip>
                    <TextBlock Text="Fit to window width and enable scrolling." />
                </ToolTipService.ToolTip>
                <TextBlock Padding="4 0" FontFamily="{StaticResource TelerikWebUILocal}" FontSize="16"
                           Text="{StaticResource GlyphArrowsResizing}"
                           Foreground="{Binding RelativeSource={RelativeSource AncestorType=ContentPresenter}, Path=(TextElement.Foreground)}" />
            </telerik:RadToggleButton>
            
            <telerik:RadToggleButton x:Name="fitToPageButton" 
                                    Command="{Binding FitToPageFixedDocumentSinglePageViewPresenterCommandDescriptor.Command}" 
                                    IsEnabled="{Binding FitToPageFixedDocumentSinglePageViewPresenterCommandDescriptor.IsEnabled, Converter={StaticResource InvertedBooleanConverter}, Mode=TwoWay}"
                                    IsChecked="{Binding FitToPageFixedDocumentSinglePageViewPresenterCommandDescriptor.IsEnabled, Mode=TwoWay}"
                                    Padding="0" IsBackgroundVisible="False" HorizontalAlignment="Left" 
                                    VerticalAlignment="Stretch">
                <ToolTipService.ToolTip>
                    <TextBlock Text="Fit one full page to window." />
                </ToolTipService.ToolTip>
                <TextBlock Padding="4 0" FontFamily="{StaticResource TelerikWebUILocal}" FontSize="16"
                           Text="{StaticResource GlyphSelectAll}"
                           Foreground="{Binding RelativeSource={RelativeSource AncestorType=ContentPresenter}, Path=(TextElement.Foreground)}" />
            </telerik:RadToggleButton>
            
            <telerik:RadToolBarSeparator />
            
            <telerik:RadToggleButton IsChecked="{Binding FixedDocumentViewer.Mode, Mode=TwoWay, Converter={StaticResource ModeConverter}, ConverterParameter=Pan}"  
                                     Padding="0" IsBackgroundVisible="False" HorizontalAlignment="Left" 
                                     VerticalAlignment="Stretch">
                <ToolTipService.ToolTip>
                    <TextBlock Text="Pan" />
                </ToolTipService.ToolTip>
                <TextBlock Padding="4 0" FontFamily="{StaticResource TelerikWebUILocal}" FontSize="16"
                           Text="{StaticResource GlyphPan}"
                           Foreground="{Binding RelativeSource={RelativeSource AncestorType=ContentPresenter}, Path=(TextElement.Foreground)}" />
            </telerik:RadToggleButton>
            
            <telerik:RadToggleButton Name="btnTextSelect" IsChecked="{Binding FixedDocumentViewer.Mode, Mode=TwoWay, Converter={StaticResource ModeConverter}, ConverterParameter=TextSelection}"  
                                     Padding="0" IsBackgroundVisible="False" HorizontalAlignment="Left" 
                                     VerticalAlignment="Stretch">
                <ToolTipService.ToolTip>
                    <TextBlock Text="Text Selection" />
                </ToolTipService.ToolTip>
                <TextBlock Padding="4 0" FontFamily="{StaticResource TelerikWebUILocal}" FontSize="16"
                           Text="{StaticResource GlyphTextbox}"
                           Foreground="{Binding RelativeSource={RelativeSource AncestorType=ContentPresenter}, Path=(TextElement.Foreground)}" />
            </telerik:RadToggleButton>
        </telerik:RadToolBar>

        <!--Telerik PDF Viewer Control-->
        <telerik:RadPdfViewer x:Name="radPdfViewer" Grid.Row="1" 
                              DataContext="{Binding CommandDescriptors, ElementName=radPdfViewer}"
                              DocumentSource="{Binding RelativeSource={RelativeSource AncestorType=UserControl}, Path=DataContext.PDFDoc}"
                              LostMouseCapture="{s:Action Get_HighLightedText}"
                              telerik:RadPdfViewerAttachedComponents.RegisterFindDialog="True" 
                              HorizontalAlignment="Stretch" Margin="0,0,0,0" VerticalAlignment="Stretch" 
                              telerik:StyleManager.Theme="Office_Black" Grid.ColumnSpan="2">
            <telerik:RadContextMenu.ContextMenu>
                <telerik:RadContextMenu>
                    <telerik:RadMenuItem Header="Select All" 
                                         Command="{Binding SelectAllCommandDescriptor.Command}" />
                    <telerik:RadMenuItem Header="Copy" 
                                         Command="{Binding CopyCommandDescriptor.Command}" />
                </telerik:RadContextMenu>
            </telerik:RadContextMenu.ContextMenu>
        </telerik:RadPdfViewer>
    </Grid>
</UserControl>

<!--DocumentSource="{Binding RelativeSource={RelativeSource AncestorType=UserControl}, Path=DataContext.PDFDoc}"-->

<!--DataContext="{Binding CommandDescriptors, ElementName=radPdfViewer}"-->
    

Child ViewModel

using ESTClient.Models;
using Stylet;
using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Windows;
using Telerik.Windows.Controls;
using Telerik.Windows.Documents.Commands.Descriptors;
using Telerik.Windows.Documents.Fixed.Selection;
using Telerik.Windows.Documents.Fixed.Text;

namespace ESTClient.ViewModels
{
    public class PDFViewModel : Screen
    {
        private MyApplication MyApplication = new MyApplication();


        private string _highlightedText;
        public string HighlightedText
        {
            get
            {
                return _highlightedText;
            }
            set
            {
                SetAndNotify(ref _highlightedText, value);
            }

        }

        private string _pdfDoc;
        public string PDFDoc
        {
            get
            {
                return _pdfDoc;
            }
            set
            {
                _pdfDoc = value;
            }
        }

        public PDFViewModel(MyApplication myApplication)
        {
            MyApplication = myApplication;
            PDFDoc = myApplication.ArgsUrl;

        }

        public void Get_HighLightedText(object sender, EventArgs e)
        {

            RadPdfViewer viewer = (RadPdfViewer)sender;
            HighlightedText = viewer.GetSelectedText();


        }

        public void SelectAll(object sender)
        {



            //TextPosition textPositionStart = new TextPosition(viewer.Document.CaretPosition);
            //textPositionStart.MoveToStartOfDocument();
            //TextPosition textPositionEnd = new TextPosition(viewer.Document.CaretPosition);
            //textPositionEnd.MoveToEndOfDocument();
            //viewer.Document.Selection.SetSelection(textPositionStart, textPositionEnd);
            //FixedDocumentViewerBase document = viewer.;
            //TextRangeProvider textRange = new TextRangeProvider(



            //viewer.Select()
        }

    }
}

[canton7]

Your options are basically:

1. Bind to a method on the ChildViewModel, and have it notify its parent that the "Select All" button was clicked (through an event, delegate interface, the event aggregator, some shared singleton service, etc). Alternatively the VM can have a property which is some shared singleton service, and you can set the action's Target to a binding to this.
2. Find a way in XAML to get a reference to the RootViewModel. You might be able to do ActionTarget="{Binding DataContext, ElementName=nameOfRootView}" -- I can't remember whether element names flow across parent/child boundaries like that, but I rather suspect not.
3. Set the action's target to something globally accessible, either a static method on a class, or an instance method on a singleton static instance of a class.

Style doesn't really do anything specific around this case: you've just got the normal tools which XAML and C# offer you.

[canton7]

Or, of course, you could use CommandManager -- there's nothing saying you have to use actions, if another method is more suitable!

[jgarner07]

Ahh ok thank you so much for your response. This gives me a ton of options to learn about. When I get this figured out, I will post my solution just in case anyone is curious later on.