#### Migrating WebKitGTK Applications to GTK 4

This document contains guidance to application developers looking to migrate applications that use WebKitGTK from GTK 3 to GTK 4.

webkitgtk-6.0 is a new API version of WebKitGTK designed for use with GTK 4 and libsoup 3. This API version obsoletes webkit2gtk-4.0 and webkit2gtk-4.1, the GTK 3 API versions for libsoup 2 and libsoup 3, respectively. It also obsoletes webkit2gtk-5.0, which was an earlier unstable API version for GTK 4.

## Upgrade to libsoup 3

libsoup 2 and libsoup 3 cannot be linked together. If your application currently uses webkit2gtk-4.0, you must first port to webkit2gtk-4.1 by eliminating use of libsoup 2. See Migrating from libsoup 2 for guidance on this. After first migrating to webkit2gtk-4.1, then it is time to start looking into webkitgtk-6.0.

## Stop Using Deprecated APIs

All APIs that were previously deprecated in webkit2gtk-4.0 and webkit2gtk-4.1 have been removed. This includes the original JavaScriptCore API (e.g. `JSContextRef` and `JSObjectRef`), which has been replaced by the GObject-style JavaScriptCore API (e.g. JSC.Context and JSC.Object) that is available since 2.22. It also includes the entire GObject DOM API (e.g. `WebKitDOMDocument`), which has been removed without replacement. Use JavaScript to interact with and manipulate the DOM instead, perhaps via `webkit_web_view_evaluate_javascript()` or `webkit_web_view_call_async_javascript_function()` in the UI process, or JSC.ValueObject.invoke_method in the web process.

Run your application with the environment variable `G_ENABLE_DIAGNOSTIC=1` to notice use of deprecated signals and properties.

## Upgrade to GTK 4

After successfully building your webkit2gtk-4.1 application without deprecation warnings, then it is time to attempt to upgrade to GTK 4 and webkitgtk-6.0. This is easier said than done, but the GTK 4 migration guide will help. Good luck.

## Most Types Are Final

Only two types are now derivable:

- `WebKitWebView` has been often subclassed to customize its behavior for an specific application. This possibility has been kept, as it has proved useful in the past.
- `WebKitInputMethodContext` is specifically designed in a way that subclassing is required to make use of it.

The rest of the types are no longer derivable; they are defined with the `G_TYPE_FLAG_FINAL` flag set. Use composition instead of derivation.

## Mandatory Web Process Sandbox

The `webkit_web_context_set_sandbox_enabled()` and `webkit_web_context_get_sandbox_enabled()` functions have been removed. The web process sandbox is now always enabled. If your application’s web process needs to access extra directories, use `webkit_web_context_add_path_to_sandbox()` to mount them in the sandbox.

## Mandatory Process Swap on Cross-site Navigation

The `WebKitWebContext:process-swap-on-cross-site-navigation-enabled` property has been removed. Process swapping is now mandatory. Your application should be prepared for the web view’s web process to be replaced when navigating between different security origins. You can ensure that your application is prepared for this change before porting to GTK 4 by testing your application with the `WebKitWebContext:process-swap-on-cross-site-navigation-enabled` property enabled. This property was previously disabled by default.

## Event Parameter Removed from Context Menu and Option Menu Signals

`WebKitWebView::context-menu` and `WebKitWebView::show-option-menu` no longer have a `GdkEvent` parameter. Adjust your signal handlers accordingly.

## Changes to WebKitWebView Construction

`webkit_web_view_new_with_context()`, `webkit_web_view_new_with_settings()`, `webkit_web_view_new_with_user_content_manager()`, and `webkit_web_view_new_with_related_view()` have all been removed. You may directly use `g_object_new()` instead. `webkit_web_view_new()` remains.

## Network Session API

WebKit now uses a single global network process for all web contexts, and different network sessions can be created and used in the same network process. All the networking APIs have been moved from `WebKitWebContext` and `WebKitWebsiteDataManager` to the new class `WebKitNetworkSession`. There’s a default global persistent session that you can get with `webkit_network_session_get_default()`. You can also create new sessions with `webkit_network_session_new()` for persistent sessions and `webkit_network_session_new_ephemeral()` for ephemeral sessions. It’s no longer possible to create a `WebKitWebsiteDataManager`; it’s now created by the `WebKitNetworkSession` automatically at construction time. The `WebKitNetworkSession` to be used must be passed to the `WebKitWebView` as a construct parameter. You can pass the same `WebKitNetworkSession` object to several web views to use the same session. The only exception is automation mode, which uses its own ephemeral session that is configured by the automation session capabilities. If you notice that your application uses `WebKitWebContext` or `WebKitWebsiteDataManager` APIs that no longer exist, look for replacement APIs in `WebKitNetworkSession`.

`webkit_web_context_clear_cache()` does not have a direct replacement, but you can use `webkit_website_data_manager_clear()` to achieve the same effect.

The `WebKitWebContext::download-started` signal has been removed. Use `WebKitNetworkSession::download-started` instead.

## Favicon Database

`WebKitFaviconDatabase` is now owned by `WebKitWebsiteDataManager` instead of `WebKitWebContext`. Use `webkit_website_data_manager_set_favicons_enabled()` to enable the favicon database.

There is no replacement for `webkit_web_context_set_favicon_database_directory()`. Favicons will be stored in the base cache directory of the website data manager.

## Hardware Acceleration Policy

`WEBKIT_HARDWARE_ACCELERATION_POLICY_ON_DEMAND` has been removed from `WebKitHardwareAccelerationPolicy`. You may still use `webkit_settings_set_hardware_acceleration_policy()` to enable or disable hardware acceleration.

## Scrollbar Appearance

Because GTK 4 does not contain a foreign drawing API, it is no longer possible to draw scrollbars that match arbitrary GTK themes. Accordingly, the `webkit_web_context_get_use_system_appearance_for_scrollbars` and `webkit_web_context_set_use_system_appearance_for_scrollbars` APIs have been removed. WebKit will draw scrollbars that match the Adwaita GTK theme.

## User Script Message Handlers

`webkit_user_content_manager_register_script_message_handler_in_world()` and `webkit_user_content_manager_unregister_script_message_handler_in_world()` have been removed. Instead, `webkit_user_content_manager_register_script_message_handler()` and `webkit_user_content_manager_unregister_script_message_handler()` have gained parameters to specify the script world to use.

## Download Destination

`webkit_download_set_destination()`, `webkit_download_get_destination()`, `WebKitDownload:destination`, and `WebKitDownload::created-destination` now all use a filesystem path rather than a URI. All uses must be updated accordingly.

## JavaScript Results

WebKitJavascriptResult has been removed. `WebKitUserContentManager::script-message-received` now directly returns a JSC.Value instead.

## Web Process Extension

WebKitWebExtension has been renamed to WebKitWebProcessExtension to avoid confusion with WebExtensions, which are unrelated. This affects many methods and signals of other objects as well, e.g. `WebKitWebContext::initialize-web-process-extensions`. The name of your extension’s entry point must now be `webkit_web_process_extension_initialize()` or `webkit_web_process_extension_initialize_with_user_data()`.

Beware that as of WebKitGTK 2.40, the entire web process API may unfortunately be removed in the future. For more information on why, see this mailing list thread.