WinForms - Toggle Form.ShowInTaskbar causes browser reload

[sai10rman]

changing the minimal example with this line
add a menu item that does:
this.ShowInTaskbar = !this.ShowInTaskbar;
causes the url to reload

Bug Report
using versions 55, 57
x86 + x64
Win10
using WinForms

https://github.com/cefsharp/CefSharp.MinimalExample

[amaitland]

It may be possible to handle this scenario by reparenting the browser window handle.

http://www.magpcss.org/ceforum/viewtopic.php?f=6&t=10290

Pull Requests welcome.

[amaitland]

The WinForms version will require changes to allow for it to be re-parented when a new handle is created.

[amaitland]

Resolved with 85e3297

[MihaMarkic]

@amaitland It doesn't see to work for me.
Below is the code from Form1.cs (new Winforms project template) and using 65 pre2 CefSharp.
(I trigger it when user wants to close the form, but the trigger doesn't really matter)
Should I set anything? From looking at source it sounds like it should be done automatically.

Expected: to see browser as it was
Actual: no browser - same as it was in 63

protected override void OnLoad(EventArgs e)
{
    if (!DesignMode)
    {
        browserControl = new ChromiumWebBrowser("https://blog.rthand.com/")
        {
            Dock = DockStyle.Fill
        };
        Controls.Add(browserControl);
    }
    base.OnLoad(e);
}

protected override async void OnClosing(CancelEventArgs e)
{
    e.Cancel = true;
    ShowInTaskbar = false;
    WindowState = FormWindowState.Minimized;
    base.OnClosing(e);

    await Task.Delay(1000);
    WindowState = FormWindowState.Normal;
    ShowInTaskbar = true;
}

[amaitland]

It works with the CefSharp.WinForms.Example when using the Tabbed control, which is what I would have tested with originally.

When the ChromiumWebBrowser is attached directly to the form it doesn't work as expected. At this point I'm not sure what the difference is.

[amaitland]

The browser needs to be temporarily re-parented to a new control whilst the handle is destroyed and a new one created.

A workaround would look something like.

var parent = toolStripContainer.ContentPanel;

var tempControl = new Control();
tempControl.CreateControl();

parent.Controls.Remove(browser);
tempControl.Controls.Add(browser);

ShowInTaskbar = !ShowInTaskbar;

tempControl.Controls.Remove(browser);
parent.Controls.Add(browser);

tempControl.Dispose();
tempControl = null;

WinForms moves it's controls to a parking window when a handle is being recreated, ideally we'd do the same, unfortunately all the methods required are declared internal.

• https://docs.microsoft.com/en-us/archive/blogs/sburke/flashback-windows-forms-parking-window
• https://stackoverflow.com/questions/20585012/what-are-parking-windows-in-winforms

[igorkrets]

this.Visible = !this.Visible;