C# WPF Deactivated event is not sent when the MS Teams screen sharing lags

Question

C# WPF Deactivated event is not sent when the MS Teams screen sharing lags

justRomm 0

I have a C# WPF application in which I subscribe application's Main Window to Deactivated event which was working fine and hides my app when I clicks on other app or on a desktop. But I got a problem with it. When I start sharing my entire screen in MS teams (win 11, in win10 I wasn't been able to reproduce it), there is a lag which hides taskbar for a second and after it Deactivated event (when I click into another app, or a desktop) is not being sent completely. I have tried to use WndProc and try to monitor the events. When there is no such Teams lag, WM_NCACTIVATE and WM_ACTIVATE messages are being sent, but with it, there is no these messages at all. So, the question is: how can I monitor the activation state of the app with something different from a WM_NCACTIVATE, WM_ACTIVATE and Deactivated event?

Hui Liu-MSFT 48,676 Microsoft External Staff

Hi,@justRomm. Welcome to Microsoft Q&A Forum. You could use the ComponentDispatcher class to monitor the activation status of your application, which can bypass some event latency issues. ComponentDispatcher provides a ThreadFilterMessage event, which is triggered before the message enters the thread message queue. You can use this event to monitor WM_NCACTIVATE, WM_ACTIVATE and other messages. Here is a sample code that demonstrates how to use the ComponentDispatcher.ThreadFilterMessage event to monitor messages:


using System;
using System.Windows;
using System.Windows.Interop;
using System.Runtime.InteropServices;
 
namespace WpfApp
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            Loaded += MainWindow_Loaded;
        }
 
        private void MainWindow_Loaded(object sender, RoutedEventArgs e)
        {
            // Subscribe to the Deactivated event
            Deactivated += MainWindow_Deactivated;
 
            // Subscribe to the ThreadFilterMessage event
            ComponentDispatcher.ThreadFilterMessage += ComponentDispatcher_ThreadFilterMessage;
        }
 
        private void MainWindow_Deactivated(object sender, EventArgs e)
        {
           // Handle the Deactivated event
           //Perform your operations here
        }
 
        private void ComponentDispatcher_ThreadFilterMessage(ref MSG msg, ref bool handled)
        {
            // Handle WM_NCACTIVATE, WM_ACTIVATE and other messages
            if (msg.message == WM_NCACTIVATE || msg.message == WM_ACTIVATE)
            {
                // Do your action here
            }
        }
 
        // define some constants
        private const int WM_NCACTIVATE = 0x0086;
        private const int WM_ACTIVATE = 0x0006;
 
        // define MSG struct
        [StructLayout(LayoutKind.Sequential)]
        public struct MSG
        {
            public IntPtr hwnd;
            public uint message;
            public IntPtr wParam;
            public IntPtr lParam;
            public uint time;
            public System.Drawing.Point pt;
        }
    }
}

If you still have questions, could you show a minimal example and steps without private information that can reproduce the problem?

Your answer

Hui Liu-MSFT 48,676 Reputation points Microsoft External Staff

2024-02-05T07:04:57.73+00:00

Hi,@justRomm. Welcome to Microsoft Q&A Forum. You could use the ComponentDispatcher class to monitor the activation status of your application, which can bypass some event latency issues. ComponentDispatcher provides a ThreadFilterMessage event, which is triggered before the message enters the thread message queue. You can use this event to monitor WM_NCACTIVATE, WM_ACTIVATE and other messages. Here is a sample code that demonstrates how to use the ComponentDispatcher.ThreadFilterMessage event to monitor messages:

using System; using System.Windows; using System.Windows.Interop; using System.Runtime.InteropServices; namespace WpfApp { public partial class MainWindow : Window { public MainWindow() { InitializeComponent(); Loaded += MainWindow_Loaded; } private void MainWindow_Loaded(object sender, RoutedEventArgs e) { // Subscribe to the Deactivated event Deactivated += MainWindow_Deactivated; // Subscribe to the ThreadFilterMessage event ComponentDispatcher.ThreadFilterMessage += ComponentDispatcher_ThreadFilterMessage; } private void MainWindow_Deactivated(object sender, EventArgs e) { // Handle the Deactivated event //Perform your operations here } private void ComponentDispatcher_ThreadFilterMessage(ref MSG msg, ref bool handled) { // Handle WM_NCACTIVATE, WM_ACTIVATE and other messages if (msg.message == WM_NCACTIVATE || msg.message == WM_ACTIVATE) { // Do your action here } } // define some constants private const int WM_NCACTIVATE = 0x0086; private const int WM_ACTIVATE = 0x0006; // define MSG struct [StructLayout(LayoutKind.Sequential)] public struct MSG { public IntPtr hwnd; public uint message; public IntPtr wParam; public IntPtr lParam; public uint time; public System.Drawing.Point pt; } } }

If you still have questions, could you show a minimal example and steps without private information that can reproduce the problem?

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C# WPF Deactivated event is not sent when the MS Teams screen sharing lags

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