WebKit always enables the Copy menu item in every app

WebKit always enables the Copy menu item in every app

June 24 2026

WebKit, to quote its website, “is the web browser engine used by Safari, Mail, App Store, and many other apps on macOS, iOS, and Linux.” Obviously, Safari uses WebKit to display web pages, but did you know that Mail app uses WebKit to display email messages? This is true not just for HTML emails but also for plain text format emails. There are a couple of ways to reveal the presence of WebKit in Mail, both of which may be bugs. If you disable “Auto-play animated images” in the Accessibility pane of System Settings, then when you open the contextual menu in a Mail app message or in a Safari web page, you’ll see the “Play All Animations” contextual menu item. In Mail, “Play All Animations” is the only item in the menu, suggesting to me that Apple engineers did not expect a contextual menu there. This behavior occurs on macOS Sequoia, at least; I haven’t yet tested Mail on Tahoe, because I’m avoiding that update, due to Liquid Glass.

The second way to see WebKit in Mail app is mentioned in the title of this blog post. Several weeks ago, John Gruber of Daring Fireball asked me whether I could reproduce an issue he was seeing in Safari: when a web page is focused, the Copy menu item in the main menu is always enabled, regardless of whether there’s anything selected in the web page. I could indeed reproduce that issue, and it turns out to be the fault of WebKit. The issue also occurs in Mail app, when an email message is focused.

On Apple platforms, WebKit is a public API, used by third-party apps in addition to Apple’s first-party apps. RSS readers such as NetNewsWire and Vienna, preferred by Gruber and myself, respectively, use WebKit to display articles from RSS feeds. And sure enough, both apps exhibit the same issue: the Copy menu item is always enabled when an article is focused.

What happens if you copy and paste from a WebKit WebView with no selection? Nothing happens, nothing is pasted. However, technically speaking, the clipboard is not empty.

The Clipboard Viewer app, pictured above, is included in the Additional Tools for Xcode, which can be downloaded from the Apple Developer website. The com.apple.webarchive and “Apple Web Archive pasteboard type” items in the above list are identical binary property lists (indicated by the prefix bplist). Here’s the plist transformed into XML:

WebMainResource

WebResourceData

PCFET0NUWVBFIGh0bWw+

WebResourceFrameName

WebResourceMIMEType<br>text/html<br>WebResourceTextEncodingName<br>UTF-8<br>WebResourceURL<br>https://daringfireball.net/

When you copy from a web page in Safari with no selection in the page, you get a representation of the page that includes the page URL, as well as some (useless) data in Base64 format:

% echo 'PCFET0NUWVBFIGh0bWw+' | base64 -d

Unfortunately, no other app seems to understand this web archive pasteboard type. The com.apple.WebKit.custom-pasteboard-data item also includes the web page URL wrapped in some weird format that no other app seems to understand. The other pasteboard types in the list are actually empty, with zero bytes of data. Thus, when you paste, you get nothing.

Copying from an email message in Mail app generates similar clipboard contents:

WebMainResource

WebResourceData

WebResourceFrameName

WebResourceMIMEType<br>text/html<br>WebResourceTextEncodingName<br>UTF-8<br>WebResourceURL<br>x-webdoc://48BE32AC-8EEF-4630-8C5E-BC292F17A707

In this case there’s no resource data, and the page URL with an x-webdoc scheme is seemingly useless and can’t be opened:

% open 'x-webdoc://48BE32AC-8EEF-4630-8C5E-BC292F17A707'

No application knows how to open URL x-webdoc://48BE32AC-8EEF-4630-8C5E-BC292F17A707 (Error Domain=NSOSStatusErrorDomain Code=-10814 "kLSApplicationNotFoundErr: E.g. no application claims the file" UserInfo={_LSLine=1796, _LSFunction=runEvaluator}).

Needless to say, none of this is an expected or a good user experience. Since I frequently file WebKit bug reports, I decided to file a bug report on behalf of Gruber: Copy main menu item is enabled with no selection in the web page. I subsequently learned that the first appearance of the bug was January 2025 in the WebKit source code, February 2025 in Safari Technology Preview 213, and March 2025 in Safari 18.4, as a result of attempting to fix another bug, document.execCommand("copy") only triggers if there is a selection, reported in 2016, nine years prior!

I’ve blogged about document.execCommand("copy") before: Web pages can overwrite your system clipboard without your knowledge. In that blog post I described how web pages can exploit a seemingly innocuous user gesture to overwrite the system clipboard. My web browser extension StopTheMadness Pro can now prevent this via the website option “Protect clipboard write.” Of course the document.execCommand("copy") API was not designed to be malicious, and there are prominent, legitimate use cases such as the...