StackOverflow 43623601 – Example code for answer http://stackoverflow.com/a/43628625/216074

README.md

Example code for my answer on the Stack Overflow question “In a WPF control that acts as a container, how do I place the content?”.

EllipsisButtonControl.xaml

<ContentControl
        x:Class="WpfTest.EllipsisButtonControl"
        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:local="clr-namespace:WpfTest"
        d:DesignHeight="30" d:DesignWidth="300" mc:Ignorable="d">
    <ContentControl.Template>
        <ControlTemplate TargetType="ContentControl">

            <Grid>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="*" />
                    <ColumnDefinition Width="Auto" />
                </Grid.ColumnDefinitions>

                <ContentPresenter Grid.Column="0"
                        Content="{TemplateBinding Content}" />

                <Button Grid.Column="1" Content="Press me"
                        Command="{TemplateBinding local:EllipsisButtonControl.Command}" />
            </Grid>

        </ControlTemplate>
    </ContentControl.Template>
</ContentControl>

EllipsisButtonControl.xaml.cs

using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;

namespace WpfTest
{
    public partial class EllipsisButtonControl : ContentControl
    {
        public EllipsisButtonControl()
        {
            InitializeComponent();
        }

        public ICommand Command
        {
            get { return (ICommand)GetValue(CommandProperty); }
            set { SetValue(CommandProperty, value); }
        }

        public static readonly DependencyProperty CommandProperty =
            DependencyProperty.Register("Command", typeof(ICommand), typeof(EllipsisButtonControl), new PropertyMetadata(null));
    }
}

MainWindow.xaml

<Window x:Class="WpfTest.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:WpfTest"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <local:EllipsisButtonControl Command="{Binding Test}">
            <TextBlock Text="{Binding Content}" />
        </local:EllipsisButtonControl>
    </Grid>
</Window>

MainWindow.xaml.cs

using System.Windows;

namespace WpfTest
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            DataContext = new SimpleViewModel();
        }
    }
}

SimpleViewModel.cs

using System;
using System.ComponentModel;
using System.Windows.Input;

namespace WpfTest
{
    public class SimpleViewModel : INotifyPropertyChanged
    {
        private int counter = 0;

        public event PropertyChangedEventHandler PropertyChanged;

        public ICommand Test { get; }
        public string Content { get; set; } = "Initial text";

        public SimpleViewModel()
        {
            Test = new SimpleRelayCommand(() =>
            {
                counter++;
                Content = $"Button pressed {counter} times";
                PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(Content)));
            });
        }

        public class SimpleRelayCommand : ICommand
        {
            private readonly Action _action;

            public SimpleRelayCommand(Action action)
            {
                _action = action;
            }

            public event EventHandler CanExecuteChanged;
            public bool CanExecute(object parameter) => true;
            public void Execute(object parameter) => _action();
        }
    }
}