Troubleshooting C# WebBrowser Control Hangups with AJAX
The C# WebBrowser
control, unlike a full Internet Explorer instance, often experiences freezes during AJAX calls. This article explores a solution focusing on script compatibility.
Addressing Script Compatibility Issues
The root of the problem often lies in discrepancies between the WebBrowser
control's scripting engine and that of a standard IE browser. To mitigate this, we'll leverage Feature Control to configure the control to mimic IE's behavior more closely. The FEATURE_BROWSER_EMULATION
setting is key here.
Implementing Feature Control (Registry Modification)
The following code snippet demonstrates how to implement Feature Control without needing administrator privileges:
<code class="language-csharp">private void SetBrowserFeatureControlKey(string feature, string appName, uint value) { using (var key = Registry.CurrentUser.CreateSubKey( $@"Software\Microsoft\Internet Explorer\Main\FeatureControl\{feature}", RegistryKeyPermissionCheck.ReadWriteSubTree)) { key.SetValue(appName, (uint)value, RegistryValueKind.DWord); } }</code>
Optimal Feature Settings
Based on testing, these Feature Control settings are recommended to enhance AJAX performance within the WebBrowser
control:
<code>FEATURE_BROWSER_EMULATION = 11000 FEATURE_AJAX_CONNECTIONEVENTS = 1 FEATURE_ENABLE_CLIPCHILDREN_OPTIMIZATION = 1 FEATURE_MANAGE_SCRIPT_CIRCULAR_REFS = 1 FEATURE_DOMSTORAGE = 1 FEATURE_GPU_RENDERING = 1 FEATURE_IVIEWOBJECTDRAW_DMLT9_WITH_GDI = 0 FEATURE_DISABLE_LEGACY_COMPRESSION = 1 FEATURE_LOCALMACHINE_LOCKDOWN = 0 FEATURE_BLOCK_LMZ_OBJECT = 0 FEATURE_BLOCK_LMZ_SCRIPT = 0 FEATURE_DISABLE_NAVIGATION_SOUNDS = 1 FEATURE_SCRIPTURL_MITIGATION = 1 FEATURE_SPELLCHECKING = 0 FEATURE_STATUS_BAR_THROTTLING = 1 FEATURE_TABBED_BROWSING = 1 FEATURE_VALIDATE_NAVIGATE_URL = 1 FEATURE_WEBOC_DOCUMENT_ZOOM = 1 FEATURE_WEBOC_POPUPMANAGEMENT = 0 FEATURE_WEBOC_MOVESIZECHILD = 1 FEATURE_ADDON_MANAGEMENT = 0 FEATURE_WEBSOCKET = 1 FEATURE_WINDOW_RESTRICTIONS = 0 FEATURE_XMLHTTP = 1</code>
Application Steps
Create a method incorporating these settings (similar to the example provided). Crucially, call this method before the WebBrowser
control is initialized, typically within the form's constructor. This ensures the settings are applied before any AJAX requests are made.
By correctly configuring Feature Control, you can significantly improve the WebBrowser
control's compatibility with AJAX calls, resolving hang-ups and ensuring smoother script execution.
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