// 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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namespace CefSharp.Handler
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{
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/// <summary>
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/// Default implementation of <see cref="ILifeSpanHandler"/>. This class provides default implementations of the methods from
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/// <see cref="ILifeSpanHandler"/>, therefore providing a convenience base class for a custom implementation.
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/// You need only override the methods you require.
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/// IMPORTANT: <see cref="ILifeSpanHandler.DoClose(IWebBrowser, IBrowser)"/> behaviour of this implementation differs
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/// from the default, the WM_CLOSE message is only sent by default for popups (return false), for the main browser
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/// we return true to cancel this behaviour.
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/// </summary>
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/// <seealso cref="T:CefSharp.ILifeSpanHandler"/>
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public class LifeSpanHandler : ILifeSpanHandler
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{
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/// <inheritdoc/>
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bool ILifeSpanHandler.DoClose(IWebBrowser chromiumWebBrowser, IBrowser browser)
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{
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return DoClose(chromiumWebBrowser, browser);
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}
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/// <summary>
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/// Called when a browser has recieved a request to close. This may result
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/// directly from a call to CefBrowserHost::CloseBrowser() or indirectly if the
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/// browser is a top-level OS window created by CEF and the user attempts to
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/// close the window. This method will be called after the JavaScript
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/// 'onunload' event has been fired. It will not be called for browsers after
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/// the associated OS window has been destroyed (for those browsers it is no
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/// longer possible to cancel the close).
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///
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/// If CEF created an OS window for the browser returning false will send an OS
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/// close notification to the browser window's top-level owner (e.g. WM_CLOSE
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/// on Windows). If no OS window exists (window rendering disabled) returning false
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/// will cause the browser object to be destroyed immediately. Return true if
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/// the browser is parented to another window and that other window needs to
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/// receive close notification via some non-standard technique.
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///
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/// !!IMPORTANT!!: Behaviour of this implementation differs from the default,
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/// the WM_CLOSE message is only sent by default for popups (return false),
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/// for the main browser we return true to cancel this behaviour.
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///
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/// If an application provides its own top-level window it should handle OS
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/// close notifications by calling CefBrowserHost::CloseBrowser(false) instead
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/// of immediately closing (see the example below). This gives CEF an
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/// opportunity to process the 'onbeforeunload' event and optionally cancel the
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/// close before DoClose() is called.
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///
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/// The CefLifeSpanHandler::OnBeforeClose() method will be called immediately
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/// before the browser object is destroyed. The application should only exit
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/// after OnBeforeClose() has been called for all existing browsers.
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///
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/// If the browser represents a modal window and a custom modal loop
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/// implementation was provided in CefLifeSpanHandler::RunModal() this callback
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/// should be used to restore the opener window to a usable state.
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///
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/// By way of example consider what should happen during window close when the
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/// browser is parented to an application-provided top-level OS window.
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/// 1. User clicks the window close button which sends an OS close
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/// notification (e.g. WM_CLOSE on Windows, performClose: on OS-X and
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/// "delete_event" on Linux).
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/// 2. Application's top-level window receives the close notification and:
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/// A. Calls CefBrowserHost::CloseBrowser(false).
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/// B. Cancels the window close.
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/// 3. JavaScript 'onbeforeunload' handler executes and shows the close
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/// confirmation dialog (which can be overridden via
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/// CefJSDialogHandler::OnBeforeUnloadDialog()).
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/// 4. User approves the close.
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/// 5. JavaScript 'onunload' handler executes.
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/// 6. Application's DoClose() handler is called. Application will:
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/// A. Set a flag to indicate that the next close attempt will be allowed.
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/// B. Return false.
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/// 7. CEF sends an OS close notification.
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/// 8. Application's top-level window receives the OS close notification and
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/// allows the window to close based on the flag from #6B.
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/// 9. Browser OS window is destroyed.
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/// 10. Application's CefLifeSpanHandler::OnBeforeClose() handler is called and
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/// the browser object is destroyed.
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/// 11. Application exits by calling CefQuitMessageLoop() if no other browsers
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/// exist.
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/// </summary>
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/// <param name="chromiumWebBrowser">the ChromiumWebBrowser control</param>
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/// <param name="browser">The browser instance - check if IsDisposed as it's possible when the browser is disposing</param>
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/// <returns>For default behaviour return false</returns>
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protected virtual bool DoClose(IWebBrowser chromiumWebBrowser, IBrowser browser)
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{
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//For popups by default are created by CEF and need to be closed via the default behaviour
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//(Sending a WM_CLOSE message)
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if (browser.IsPopup)
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{
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return false;
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}
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//For the main browser NO WM_CLOSE message will be sent.
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return true;
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}
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/// <inheritdoc/>
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void ILifeSpanHandler.OnAfterCreated(IWebBrowser chromiumWebBrowser, IBrowser browser)
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{
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OnAfterCreated(chromiumWebBrowser, browser);
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}
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/// <summary>
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/// Called after a new browser is created.
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/// </summary>
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/// <param name="chromiumWebBrowser">the ChromiumWebBrowser control</param>
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/// <param name="browser">The browser instance</param>
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protected virtual void OnAfterCreated(IWebBrowser chromiumWebBrowser, IBrowser browser)
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{
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}
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/// <inheritdoc/>
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void ILifeSpanHandler.OnBeforeClose(IWebBrowser chromiumWebBrowser, IBrowser browser)
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{
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OnBeforeClose(chromiumWebBrowser, browser);
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}
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/// <summary>
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/// Called before a CefBrowser window (either the main browser for <see cref="IWebBrowser"/>,
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/// or one of its children)
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/// </summary>
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/// <param name="chromiumWebBrowser">the ChromiumWebBrowser control</param>
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/// <param name="browser">The browser instance</param>
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protected virtual void OnBeforeClose(IWebBrowser chromiumWebBrowser, IBrowser browser)
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{
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}
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/// <inheritdoc/>
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bool ILifeSpanHandler.OnBeforePopup(IWebBrowser chromiumWebBrowser, IBrowser browser, IFrame frame, string targetUrl, string targetFrameName, WindowOpenDisposition targetDisposition, bool userGesture, IPopupFeatures popupFeatures, IWindowInfo windowInfo, IBrowserSettings browserSettings, ref bool noJavascriptAccess, out IWebBrowser newBrowser)
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{
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return OnBeforePopup(chromiumWebBrowser, browser, frame, targetUrl, targetFrameName, targetDisposition, userGesture, popupFeatures, windowInfo, browserSettings, ref noJavascriptAccess, out newBrowser);
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}
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/// <summary>
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/// Called before a popup window is created. By default the popup (browser) is created in a new native window.
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/// </summary>
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/// <param name="chromiumWebBrowser">the ChromiumWebBrowser control</param>
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/// <param name="browser">The browser instance that launched this popup.</param>
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/// <param name="frame">The HTML frame that launched this popup.</param>
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/// <param name="targetUrl">The URL of the popup content. (This may be empty/null)</param>
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/// <param name="targetFrameName">The name of the popup. (This may be empty/null)</param>
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/// <param name="targetDisposition">The value indicates where the user intended to
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/// open the popup (e.g. current tab, new tab, etc)</param>
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/// <param name="userGesture">The value will be true if the popup was opened via explicit user gesture
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/// (e.g. clicking a link) or false if the popup opened automatically (e.g. via the DomContentLoaded event).</param>
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/// <param name="popupFeatures"> structure contains additional information about the requested popup window</param>
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/// <param name="windowInfo">window information</param>
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/// <param name="browserSettings">browser settings, defaults to source browsers</param>
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/// <param name="noJavascriptAccess">value indicates whether the new browser window should be scriptable
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/// and in the same process as the source browser.</param>
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/// <param name="newBrowser">
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/// EXPERIMENTAL - Low level this allows for assigning the CefClient instance associated with the new ChromiumWebBrowser instance to the CefClient param of the CefLifeSpanHandler::OnBeforeBrowser method.
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/// This allows for all the handlers, LifeSpanHandler, DisplayHandler, etc to be associated with the CefClient of the new ChromiumWebBrowser instance to be associated with the popup (browser).
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/// WPF/WinForms specific code is still required to host the popup (browser) in the new ChromiumWebBrowser instance.
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/// Set to null for default behaviour. If you return true (cancel popup creation) then his property **MUST** be null, an exception will be thrown otherwise.
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/// </param>
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/// <returns>
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/// By default the popup (browser) is opened in a new native window. If you return true then creation of the popup (browser) is cancelled, no further action will occur.
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/// Otherwise return false to allow creation of the popup (browser).
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/// </returns>
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/// <remarks>
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/// If you return true and set <paramref name="newBrowser"/> to not null then an exception will be thrown as creation of the popup (browser) was cancelled.
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/// WinForms - To host the popup (browser) in a TAB/Custom Window see https://github.com/cefsharp/CefSharp/wiki/General-Usage#winforms---hosting-popup-using-tab-control for an easy method.
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/// WPF - For an example of hosting the popup (browser) in a custom window see https://github.com/cefsharp/CefSharp/wiki/General-Usage#wpf---hosting-popup-in-new-window-experimental
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/// Same can be applied for hosting the popup in a TAB.
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/// This method is still EXPERIMENTAL and will likely require upstream bug fixes in CEF (https://bitbucket.org/chromiumembedded/cef).
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/// </remarks>
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protected virtual bool OnBeforePopup(IWebBrowser chromiumWebBrowser, IBrowser browser, IFrame frame, string targetUrl, string targetFrameName, WindowOpenDisposition targetDisposition, bool userGesture, IPopupFeatures popupFeatures, IWindowInfo windowInfo, IBrowserSettings browserSettings, ref bool noJavascriptAccess, out IWebBrowser newBrowser)
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{
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newBrowser = null;
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return false;
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}
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}
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}
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