WinForms - Browser switches focus after SendMouseClickEvent when two browser forms shown

[erches]

What version of the product are you using?

106.0.290

What architecture x86 or x64?

x64

On what operating system?

Win10

Are you using WinForms, WPF or OffScreen?

WinForms/WPF (using WindowsFormsHost component)

What steps will reproduce the problem?

I create and show two browser windows with ChromiumWebBrowser control at the same time and then start sending left mouse click events using SendMouseClickEvent function with a short period of time. Browser windows start to switch focus.

I have no such problem with version 79.1.360 . This behavior appears with CefSharp versions above 79.1.360.

Program.cs

static void Main()
{
    Application.Run(new AppContext());
}

AppContext.cs

public class AppContext : ApplicationContext
{
    private Browser form1;
    private Browser form2;

    public AppContext()
    {
        InitCef();

        form1 = new Browser();
        form1.WindowState = FormWindowState.Normal;

        form2 = new Browser();
        form2.WindowState = FormWindowState.Normal;

        form1.FormClosed += OnFormClosed;
        form2.FormClosed += OnFormClosed;

        form1.Show();
        form2.Show();

        var task1 = CreateClicksTask(form1.browser);
        var task2 = CreateClicksTask(form2.browser);

        task1.Start();
        task2.Start();
    }

    private void OnFormClosed(object sender, FormClosedEventArgs e)
    {
        if (Application.OpenForms.Count == 0)
        {
            ExitThread();
        }
    }

    private void InitCef()
    {
        Cef.Initialize(new CefSettings()
            {
                LogSeverity = LogSeverity.Error
            });
    }
        

    Task CreateClicksTask(ChromiumWebBrowser browser)
    {
        return new Task(() =>
        {
            for (int i = 0; i < 300; i++)
            {
                browser.GetBrowserHost().SendMouseClickEvent(100, 200, MouseButtonType.Left, false, 1, CefEventFlags.None);
                browser.GetBrowserHost().SendMouseClickEvent(100, 200, MouseButtonType.Left, true, 1, CefEventFlags.None);
                Thread.Sleep(1000);
            }
        });
    }
}

Browser.cs

public partial class Browser : Form
{
    public ChromiumWebBrowser browser;
    public Browser()
    {
        InitializeComponent();
        browser = new ChromiumWebBrowser("www.google.com")
        {
            Dock = DockStyle.Fill,
        };
        Controls.Add(browser);
    }
}

[amaitland]

The behaviour is implemented entirely in chromium, not something I can control/fix.

[amaitland]

As an alternative you can try using the DevTools protocol which has mouse emulation methods.

https://chromedevtools.github.io/devtools-protocol/tot/Input/#method-dispatchMouseEvent

See #3165 for details on how to use the strongly typed DevTools methods in CefSharp.