// Copyright © 2021 The CefSharp Authors. All rights reserved.
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//
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// Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
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using System;
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using System.ComponentModel;
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using System.Drawing;
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using System.Runtime.CompilerServices;
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using System.Runtime.InteropServices;
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using System.Windows.Forms;
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namespace CefSharp.WinForms.Host
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{
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/// <summary>
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/// Chromium Browser Host Control, provides base functionality for hosting a
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/// CefBrowser instance (main browser and popups) in WinForms.
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/// </summary>
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/// <seealso cref="System.Windows.Forms.Control" />
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public abstract class ChromiumHostControlBase : Control
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{
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[DllImport("user32.dll", SetLastError = true)]
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[return: MarshalAs(UnmanagedType.Bool)]
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private static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags);
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/// <summary>
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/// IntPtr that represents the CefBrowser Hwnd
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/// Used for sending messages to the browser
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/// e.g. resize
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/// </summary>
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[Browsable(false), DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
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public IntPtr BrowserHwnd { get; set; }
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/// <summary>
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/// Set to true while handing an activating WM_ACTIVATE message.
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/// MUST ONLY be cleared by DefaultFocusHandler.
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/// </summary>
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/// <value><c>true</c> if this instance is activating; otherwise, <c>false</c>.</value>
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[Browsable(false), DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden), DefaultValue(false)]
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public bool IsActivating { get; set; }
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/// <summary>
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/// Event called after the underlying CEF browser instance has been created.
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/// It's important to note this event is fired on a CEF UI thread, which by default is not the same as your application UI
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/// thread. It is unwise to block on this thread for any length of time as your browser will become unresponsive and/or hang..
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/// To access UI elements you'll need to Invoke/Dispatch onto the UI Thread.
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/// </summary>
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public event EventHandler IsBrowserInitializedChanged;
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/// <summary>
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/// Gets the default size of the control.
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/// </summary>
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/// <value>
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/// The default <see cref="T:System.Drawing.Size" /> of the control.
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/// </value>
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protected override Size DefaultSize
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{
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get { return new Size(200, 100); }
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}
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/// <summary>
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/// Makes certain keys as Input keys when CefSettings.MultiThreadedMessageLoop = false
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/// </summary>
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/// <param name="keyData">key data</param>
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/// <returns>true for a select list of keys otherwise defers to base.IsInputKey</returns>
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protected override bool IsInputKey(Keys keyData)
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{
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//This code block is only called/required when CEF is running in the
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//same message loop as the WinForms UI (CefSettings.MultiThreadedMessageLoop = false)
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//Without this code, arrows and tab won't be processed
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switch (keyData)
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{
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case Keys.Right:
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case Keys.Left:
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case Keys.Up:
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case Keys.Down:
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case Keys.Tab:
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{
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return true;
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}
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case Keys.Shift | Keys.Tab:
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case Keys.Shift | Keys.Right:
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case Keys.Shift | Keys.Left:
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case Keys.Shift | Keys.Up:
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case Keys.Shift | Keys.Down:
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{
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return true;
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}
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}
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return base.IsInputKey(keyData);
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}
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/// <summary>
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/// Raises the <see cref="E:System.Windows.Forms.Control.SizeChanged" /> event.
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/// </summary>
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/// <param name="e">An <see cref="T:System.EventArgs" /> that contains the event data.</param>
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protected override void OnSizeChanged(EventArgs e)
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{
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ResizeBrowser(Width, Height);
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base.OnSizeChanged(e);
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}
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/// <inheritdoc />
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protected override void OnVisibleChanged(EventArgs e)
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{
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if (Visible)
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{
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ShowInternal();
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}
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else
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{
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HideInternal();
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}
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base.OnVisibleChanged(e);
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}
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/// <summary>
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/// Resizes the browser to the specified <paramref name="width"/> and <paramref name="height"/>.
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/// If <paramref name="width"/> and <paramref name="height"/> are both 0 then the browser
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/// will be hidden and resource usage will be minimised.
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/// </summary>
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/// <param name="width">width</param>
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/// <param name="height">height</param>
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protected virtual void ResizeBrowser(int width, int height)
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{
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if (BrowserHwnd != IntPtr.Zero)
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{
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SetWindowPosition(BrowserHwnd, 0, 0, width, height);
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}
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}
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/// <summary>
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/// When minimized set the browser window size to 0x0 to reduce resource usage.
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/// https://github.com/chromiumembedded/cef/blob/c7701b8a6168f105f2c2d6b239ce3958da3e3f13/tests/cefclient/browser/browser_window_std_win.cc#L87
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/// </summary>
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internal virtual void HideInternal()
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{
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if (BrowserHwnd != IntPtr.Zero)
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{
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SetWindowPosition(BrowserHwnd, 0, 0, 0, 0);
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}
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}
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/// <summary>
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/// Show the browser (called after previous minimised)
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/// </summary>
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internal virtual void ShowInternal()
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{
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if (BrowserHwnd != IntPtr.Zero)
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{
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SetWindowPosition(BrowserHwnd, 0, 0, Width, Height);
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}
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}
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/// <inheritdoc/>
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protected override void Dispose(bool disposing)
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{
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if (disposing)
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{
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BrowserHwnd = IntPtr.Zero;
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IsBrowserInitializedChanged = null;
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}
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base.Dispose(disposing);
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}
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/// <summary>
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/// Trigger the <see cref="IsBrowserInitializedChanged"/> event
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/// </summary>
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internal void RaiseIsBrowserInitializedChangedEvent()
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{
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IsBrowserInitializedChanged?.Invoke(this, EventArgs.Empty);
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}
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private void SetWindowPosition(IntPtr handle, int x, int y, int width, int height)
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{
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const uint SWP_NOMOVE = 0x0002;
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const uint SWP_NOZORDER = 0x0004;
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const uint SWP_NOACTIVATE = 0x0010;
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if (handle != IntPtr.Zero)
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{
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if (width == 0 && height == 0)
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{
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// For windowed browsers when the frame window is minimized set the
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// browser window size to 0x0 to reduce resource usage.
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SetWindowPos(handle, IntPtr.Zero, 0, 0, 0, 0, SWP_NOZORDER | SWP_NOMOVE | SWP_NOACTIVATE);
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}
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else
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{
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SetWindowPos(handle, IntPtr.Zero, x, y, width, height, SWP_NOZORDER);
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}
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}
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}
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/// <summary>
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/// Gets the <see cref="ChromiumHostControl"/> or <see cref="ChromiumWebBrowser"/> associated with
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/// a specific <see cref="IBrowser"/> instance.
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/// </summary>
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/// <param name="browser">browser</param>
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/// <returns>returns the assocaited <see cref="ChromiumHostControl"/> or <see cref="ChromiumWebBrowser"/> or null if Disposed or no host found.</returns>
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public static T FromBrowser<T>(IBrowser browser) where T : ChromiumHostControlBase
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{
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if (browser.IsDisposed)
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{
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return null;
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}
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var windowHandle = browser.GetHost().GetWindowHandle();
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if (windowHandle == IntPtr.Zero)
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{
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return null;
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}
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var control = Control.FromChildHandle(windowHandle) as T;
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return control;
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}
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}
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}
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