Условие в EventTrigger

Кнопки и элементы меню имеют свойство IsPressed, которое будет работать для вас, но другие элементы управления работают. Однако легко добавить свойство IsPressed, используя некоторое присоединенное поведение. Это позволит вам написать XAML следующим образом:

<TextBlock Text="Hello" TriggerTest:IsPressedBehavior.MonitorMouse="true">
    <TextBlock.Style>
        <Style TargetType="{x:Type TextBlock}"> 
            <Setter Property="Foreground" Value="Red" />
            <Style.Triggers> 
                <Trigger Property="TriggerTest:IsPressedBehavior.IsPressed" Value="True"> 
                    <Setter Property="Foreground" Value="Green" /> 
                </Trigger>
            </Style.Triggers> 
        </Style> 
    </TextBlock.Style>
</TextBlock>

Прикрепленный класс поведения:

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

namespace TriggerTest
{
    public static class IsPressedBehavior
    {
        public static bool GetMonitorMouse(DependencyObject obj)
        {
            return (bool)obj.GetValue(MonitorMouseProperty);
        }

        public static void SetMonitorMouse(DependencyObject obj, bool value)
        {
            obj.SetValue(IsPressedProperty, value);
        }

        public static readonly DependencyProperty MonitorMouseProperty =
            DependencyProperty.RegisterAttached("MonitorMouse",
                                                typeof(bool),
                                                typeof(IsPressedBehavior),
                                                new UIPropertyMetadata(false, OnMonitorMouse));

        public static bool GetIsPressed(DependencyObject obj)
        {
            return (bool)obj.GetValue(IsPressedProperty);
        }

        public static void SetIsPressed(DependencyObject obj, bool value)
        {
            obj.SetValue(IsPressedProperty, value);
        }

        public static readonly DependencyProperty IsPressedProperty =
            DependencyProperty.RegisterAttached("IsPressed",
                                                typeof(bool),
                                                typeof(IsPressedBehavior),
                                                new UIPropertyMetadata(false));

        private static void OnMonitorMouse(DependencyObject depObj, DependencyPropertyChangedEventArgs dependencyPropertyChangedEventArgs)
        {
            UIElement uiElement = depObj as UIElement;
            if (uiElement == null)
            {
                return;
            }
            if ((bool)dependencyPropertyChangedEventArgs.NewValue)
            {
                uiElement.MouseDown += OnMouseDown;
                uiElement.MouseUp += OnMouseUp;
                uiElement.MouseLeave += OnMouseLeave;
                uiElement.MouseEnter += OnMouseEnter;
            }
            else
            {
                uiElement.MouseDown -= OnMouseDown;
                uiElement.MouseUp -= OnMouseUp;
                uiElement.MouseLeave -= OnMouseLeave;
                uiElement.MouseEnter -= OnMouseEnter;
            }
        }

        private static void OnMouseDown(object sender, MouseButtonEventArgs e)
        {
            SetIsPressed(sender as DependencyObject, true);
        }

        private static void OnMouseUp(object sender, MouseButtonEventArgs e)
        {
            SetIsPressed(sender as DependencyObject, false);
        }

        private static void OnMouseLeave(object sender, MouseEventArgs e)
        {
            SetIsPressed(sender as DependencyObject, false);
        }

        static void OnMouseEnter(object sender, MouseEventArgs e)
        {
            SetIsPressed(sender as DependencyObject, e.LeftButton == MouseButtonState.Pressed || e.MiddleButton == MouseButtonState.Pressed || e.RightButton == MouseButtonState.Pressed);
        }
    }
}