WPF-如何激发ComboBox的MouseLeftButtonUp事件？

Question

I have a ComboBox who have to call a function that need the selectedItem of the ComboBox as parameter when the user select an item. Because this event need to be fired even when the item doesn't change I can't use the SelectionChanged event. So to resolve this problem I wanted to use the MouseLeftButtonUp, but this event doesn't seems to work.

I have tried to use the PreviewMouseLeftButtonUp event, who is triggered, but the selectedItem of the ComboBox is only modified after the event, wich is too late for me.

I have also tried the MouseLeftButtonDown event, but it's doesn't work either.

WPF :

<Window x:Class="WpfApp1.MainWindow"
        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:WpfApp1"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <ComboBox x:Name="cb" VerticalAlignment="Top" HorizontalAlignment="Left" IsHitTestVisible="True"
                  PreviewMouseLeftButtonUp="Cb_PreviewMouseLeftButtonUp"
                  MouseLeftButtonUp="Cb_MouseLeftButtonUp"
                  MouseLeftButtonDown="Cb_MouseLeftButtonDown"
                  SelectionChanged="Cb_SelectionChanged"/>
    </Grid>
</Window>

C# for testing :

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
namespace WpfApp1 {
    public partial class MainWindow : Window {
        public MainWindow() {
            InitializeComponent();
            cb.Items.Add("a");
            cb.Items.Add("b");
        }
        private void Cb_PreviewMouseLeftButtonUp(object sender, MouseButtonEventArgs e) {
            Console.WriteLine("event : Preview mouse UP");
        }
        private void Cb_MouseLeftButtonUp(object sender, MouseButtonEventArgs e) {
            Console.WriteLine("event : Mouse UP"); // Does't fire
        }
        private void Cb_MouseLeftButtonDown(object sender, MouseButtonEventArgs e) {
            Console.WriteLine("event : Mouse DOWN"); // Does't fire either
        }
        private void Cb_SelectionChanged(object sender, SelectionChangedEventArgs e) {
            Console.WriteLine("event : selection changed"); // Only fire if the selected item change
        }
    }
}

So basically I just want to know if it's possible to trigger the MouseLeftButtonUp event.

Answer 1

即使选择了已选择的元素，也会触发DropDownClosed 。

Answer 2

Thanks to mami , I have found the solution :

this.AddHandler(
    ComboBox.MouseLeftButtonUpEvent,
    new MouseButtonEventHandler(Cb_MouseLeftButtonUp),
    true
);

More info here