Обмен данными внутри приложения

<phone:PhoneApplicationPage
    x:Class="P4_1.CommonPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"
    xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    FontFamily="{StaticResource PhoneFontFamilyNormal}"
    FontSize="{StaticResource PhoneFontSizeNormal}"
    Foreground="{StaticResource PhoneForegroundBrush}"
    SupportedOrientations="Portrait" Orientation="Portrait"
    mc:Ignorable="d"
    shell:SystemTray.IsVisible="True">

    <!--LayoutRoot представляет корневую сетку, где размещается все содержимое страницы-->
    <Grid x:Name="LayoutRoot" Background="Transparent">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>

        <!--TitlePanel содержит имя приложения и заголовок страницы-->
        <StackPanel Grid.Row="0" Margin="12,17,0,28">
            <TextBlock Text="НАВИГАЦИЯ" Style="{StaticResource PhoneTextNormalStyle}"/>
            <TextBlock Text="страница" Margin="9,-7,0,0" Style="{StaticResource PhoneTextTitle1Style}"/>
        </StackPanel>

        <!--ContentPanel – поместите здесь дополнительное содержимое-->
        <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
            <TextBlock x:Name="txtUserName" HorizontalAlignment="Left" Margin="10,10,0,0" 
TextWrapping="Wrap" VerticalAlignment="Top" 
Height="50" Width="446"/>
            <Rectangle x:Name="rectColor" HorizontalAlignment="Left" 
Height="111" Margin="141,156,0,0" Stroke="Black" 
VerticalAlignment="Top" Width="183" Fill="#FFF4F4F5"/>
        </Grid>
    </Grid>
    <phone:PhoneApplicationPage.ApplicationBar>
        <shell:ApplicationBar IsVisible="True" IsMenuEnabled="True" Mode="Minimized">
            <shell:ApplicationBarIconButton IconUri="/Images/questionmark.png" 
Text="О программе" Click="ApplicationBarIconButton_Click"/>
            <shell:ApplicationBar.MenuItems>
                <shell:ApplicationBarMenuItem Text="Настройки" Click="ApplicationBarMenuItem_Click"/>
                <shell:ApplicationBarMenuItem Text="Команда меню"/>
            </shell:ApplicationBar.MenuItems>
        </shell:ApplicationBar>
    </phone:PhoneApplicationPage.ApplicationBar>
</phone:PhoneApplicationPage>

using System;
using System.Windows;
using System.Windows.Navigation;
using Microsoft.Phone.Controls;
using System.Collections.Generic;
using Microsoft.Phone.Shell;

namespace P4_1
{
    public partial class CommonPage : PhoneApplicationPage
    {
        public CommonPage()
        {
            InitializeComponent();
        }

        private void ApplicationBarMenuItem_Click(object sender, EventArgs e)
        {
            NavigationService.Navigate(new Uri("/Pages/Settings.xaml", UriKind.Relative));
        }

        private void ApplicationBarIconButton_Click(object sender, EventArgs e)
        {
            NavigationService.Navigate(new Uri("/About.xaml", UriKind.Relative));
        }

        protected override void OnNavigatedTo(NavigationEventArgs e)
        {
            IDictionary<string, string> parameters = this.NavigationContext.QueryString;

            if (parameters.ContainsKey("User_name"))
            {
                txtUserName.Text = "Здравствуйте, "+parameters["User_name"];
            }

            rectColor.Fill = (Application.Current as App).MyBrush;

            base.OnNavigatedTo(e);
        }
    }
}

<phone:PhoneApplicationPage
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"
    xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:Controls="clr-namespace:Coding4Fun.Toolkit.Controls;assembly=Coding4Fun.Toolkit.Controls"
    x:Class="P4_1.Pages.Settings"
    mc:Ignorable="d"
    FontFamily="{StaticResource PhoneFontFamilyNormal}"
    FontSize="{StaticResource PhoneFontSizeNormal}"
    Foreground="{StaticResource PhoneForegroundBrush}"
    SupportedOrientations="Portrait"  Orientation="Portrait"
    shell:SystemTray.IsVisible="True">

    <!--LayoutRoot представляет корневую сетку, где размещается все содержимое страницы-->
    <Grid x:Name="LayoutRoot" Background="Transparent">
        <!--Элемент управления Pivot-->
        <phone:Pivot Title="НАВИГАЦИЯ">
            <!--Первый элемент Pivot-->
            <phone:PivotItem Header="цвет">
                <Controls:ColorPicker x:Name="cpMy" HorizontalAlignment="Left" Height="603" VerticalAlignment="Top" Width="456" />
            </phone:PivotItem>

            <!--Второй элемент Pivot-->
            <phone:PivotItem Header="размер">
                <Grid/>
            </phone:PivotItem>

            <!--Третий элемент Pivot-->
            <phone:PivotItem Header="общие">
                <Button x:Name="cmdLogOut" Content="Выйти из системы" HorizontalAlignment="Left" 
Height="83" Margin="52,84,0,0" VerticalAlignment="Top" 
Width="259" Click="cmdLogOut_Click"/>
            </phone:PivotItem>
        </phone:Pivot>
    </Grid>

</phone:PhoneApplicationPage>