ThumbnailerViewer.xaml

<Window x:Class="ThumbnailerViewer"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:Thumbnailer"
        mc:Ignorable="d"       
        Title="ThumbnailerViewer" 
        Height="1084" 
        Width="1480"  
        ScrollViewer.VerticalScrollBarVisibility="Disabled" 
        SnapsToDevicePixels="True" 
        ResizeMode="NoResize"         
        Loaded="Window_Loaded" 
        WindowStartupLocation="CenterOwner">
    <Window.ContextMenu>
        <ContextMenu x:Name="ContextMenu">
            <MenuItem x:Name="FileOpen" Header="File Open" Click="FileOpen_Click"/>
            <Separator />
            <MenuItem x:Name="Fit_Screen" Header="Fit Screen" Click="Fit_Screen_Click"/>
            <MenuItem x:Name="Zoom_Screen" Header="Normal" Click="Zoom_Screen_Click"/>
            <Separator />
            <MenuItem x:Name="CloseForm" Header="Exit" Click="CloseForm_Click"/>
        </ContextMenu>
    </Window.ContextMenu>
    <Grid>
        <Image x:Name="ViewerPB" MouseLeftButtonUp="ViewerPB_MouseLeftButtonUp" ></Image>
    </Grid>
</Window>