CustomReminderWindow.xaml

<dx:DXWindow
    x:Class="CustomReminderExample.CustomReminderWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:dx="http://schemas.devexpress.com/winfx/2008/xaml/core"
    xmlns:dxschc="http://schemas.devexpress.com/winfx/2008/xaml/scheduling/common"
    xmlns:dxmvvm="http://schemas.devexpress.com/winfx/2008/xaml/mvvm"
    xmlns:dxe="http://schemas.devexpress.com/winfx/2008/xaml/editors"
    xmlns:dxb="http://schemas.devexpress.com/winfx/2008/xaml/bars"
    xmlns:local="clr-namespace:CustomReminderExample"
    Height="320" MinHeight="320"
    Width="360" MinWidth="360"
    Title="Alerts">

    <Window.Resources>
        <DataTemplate x:Key="ListBoxItemTemplate">
            <Grid MinWidth="150">
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="Auto" />
                    <ColumnDefinition Width="*" />
                    <ColumnDefinition Width="140" />
                </Grid.ColumnDefinitions>
                <Image
                    Margin="0,0,5,0"
                    RenderOptions.BitmapScalingMode="NearestNeighbor"
                    Source="{dx:DXImage Image=Today_16x16.png}"
                    Stretch="None" />
                <TextBlock Grid.Column="1" Text="{Binding Reminder.Subject}" />
                <TextBlock
                    Grid.Column="2"
                    Margin="5,0,0,0"
                    Text="{Binding TimeBeforeAppointmentStartDisplayText, UpdateSourceTrigger=PropertyChanged}"
                    TextAlignment="Left" />
            </Grid>
        </DataTemplate>
        <local:TimeSpanToNumberConverter x:Key="timespanconverter" />
    </Window.Resources>

    <dxmvvm:Interaction.Behaviors>
        <dxmvvm:CurrentWindowService ClosingCommand="{Binding WindowClosingCommand}" />
    </dxmvvm:Interaction.Behaviors>

    <Grid Margin="10">
        <Grid.RowDefinitions>
            <RowDefinition Height="AUTO" />
            <RowDefinition Height="*" />
            <RowDefinition Height="AUTO" />
        </Grid.RowDefinitions>
        <StackPanel Orientation="Horizontal">
            <StackPanel HorizontalAlignment="Left" Orientation="Vertical">
                <TextBlock
                    Margin="0,0,0,5"
                    FontWeight="Bold"
                    Opacity="{Binding IsRemindersSubjectVisible, Converter={dx:BoolToVisibilityViaOpacityConverter}}"
                    Text="{Binding ElementName=lbReminders, Path=SelectedItem.Reminder.Subject}" />
                <TextBlock x:Name="startDisplayTextBlock" Text="{Binding AppointmentStartDisplayText}" />
            </StackPanel>
        </StackPanel>
        <dxe:ListBoxEdit
            x:Name="lbReminders"
            Grid.Row="1"
            Margin="0,5,0,5"
            MinHeight="130"
            EditValue="{Binding SelectedReminders, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
            Grid.IsSharedSizeScope="True"
            ItemsSource="{Binding TriggeredReminders}"
            ItemTemplate="{StaticResource ListBoxItemTemplate}"
            SelectionMode="Extended">
            <dxb:BarManager.DXContextMenu>
                <dxb:PopupMenu>
                    <dxb:PopupMenu.Items>
                        <dxb:BarButtonItem Command="{Binding DismissAllCommand}" Content="Dismiss All" />
                        <dxb:BarButtonItem
                            Command="{Binding OpenItemCommand}"
                            Content="Open"
                            IsEnabled="{Binding CanOpenAppointmentWindow}" />
                        <dxb:BarButtonItem
                            Command="{Binding DismissCommand}"
                            Content="Dismiss"
                            IsEnabled="{Binding CanOpenAppointmentWindow}" />
                        <dxb:BarButtonItem Command="{Binding SnoozeCommand}" Content="Snooze" />
                    </dxb:PopupMenu.Items>
                </dxb:PopupMenu>
            </dxb:BarManager.DXContextMenu>
        </dxe:ListBoxEdit>
        <StackPanel
            Grid.Row="2"
            HorizontalAlignment="Stretch"
            Orientation="Vertical">
            <TextBlock Margin="0,5,5,5" Text="Right-click for the context menu." />
            <Grid>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="AUTO" />
                    <ColumnDefinition Width="50" />
                    <ColumnDefinition Width="*" />
                </Grid.ColumnDefinitions>
                <TextBlock Margin="0,5,5,5" Text="Select Snooze to be reminded again in" Grid.Column="0" />
                <dxe:SpinEdit
                    x:Name="txtSnoozeTime"
                    Grid.Column="1"
                    Value="9"
                    EditValue="{Binding SnoozeValue, Mode=TwoWay, Converter={StaticResource timespanconverter} }"
                    />
                <TextBlock Margin="5,5,0,5" Text="minutes" Grid.Column="2" />
            </Grid>
        </StackPanel>
    </Grid>

</dx:DXWindow>