diff --git a/lib/builtin-rules.js b/lib/builtin-rules.js
index 7f7d068..bb038d1 100644
--- a/lib/builtin-rules.js
+++ b/lib/builtin-rules.js
@@ -33,7 +33,7 @@ d35aaqx5ub95lt.cloudfront.net/js/app-*.js$script
 ! --
 github.com
 gist.github.com
-    std-PerformanceObserver,std-queueMicrotask,gh-compat,gh-turbo,gh-main-csp,sm-gh-extra,sm-cookie
+    std-PerformanceObserver,std-queueMicrotask,std-NavigatorClipboard,gh-compat,gh-turbo,gh-main-csp,sm-gh-extra,sm-cookie,gh-codeview
 github.com/socket-worker.js$script
 gist.github.com/socket-worker.js$script
 github.com/assets-cdn/worker/socket-worker-*.js$script
diff --git a/lib/main.js b/lib/main.js
index 345c1ad..5bc24c1 100644
--- a/lib/main.js
+++ b/lib/main.js
@@ -52,6 +52,11 @@ function evaluateFix(fix, script, csp, contentReplace) {
         case "std-IntlRelativeTimeFormat":
             script.push(pf.Intl_RelativeTimeFormat_dummy);
             break;
+        case "std-NavigatorClipboard":
+            csp["script-src"].push("unpkg.com");
+            script.push({"src": "https://unpkg.com/clipboard-polyfill@4.0.0/dist/es5/overwrite-globals/clipboard-polyfill.overwrite-globals.promise.es5.js",
+                          "integrity": "sha384-5y9EbzFitRF4XTU0L+uQoWKyIAIkbKb/RV6kSZRKvilNx83HCi9ig9LP7kJqNJHX"});
+            break;
         case "std-PerformanceObserver":
             csp["script-src"].push("unpkg.com");
             script.push({"src": "https://unpkg.com/@fastly/performance-observer-polyfill@2.0.0/polyfill/index.js",
@@ -77,6 +82,9 @@ function evaluateFix(fix, script, csp, contentReplace) {
         case "duolingo-regexp":
             contentReplace.push([String.raw`/\p{Diacritic}/gu`, `/${pf.Regex_UnicodePropertyDiacritic}/gu`]);
             break;
+        case "gh-codeview":
+            script.push(pf.Github_restoreCodeMenu);
+            break;
         case "gh-compat":
             script.push(pf.Github_customElements);
             script.push(pf.Window_ShadowRoot);
diff --git a/lib/polyfills.js b/lib/polyfills.js
index 0197a08..5e22aaf 100644
--- a/lib/polyfills.js
+++ b/lib/polyfills.js
@@ -323,6 +323,17 @@ exports.Github_disableTurbo = jss`
   });
 `;
 
+exports.Github_restoreCodeMenu = jss`
+  // Don't pass event to mouseup handler on the textarea that disables the context menu
+  const handler = function (evt) {
+    if (evt.target && evt.target.tagName === "TEXTAREA" &&
+        evt.target.id == "read-only-cursor-text-area" && evt.button == 2) {
+      evt.stopPropagation();
+    }
+  };
+  document.addEventListener("mouseup", handler, {capture: true});
+`;
+
 // Flavor of CE that Github used to distribute as part of github-compat-838cedbb.js
 exports.Github_customElements = jss`(function(){var t=new Set("annotation-xml color-profile font-face font-face-src font-face-uri font-face-format font-face-name missing-glyph".split(" "));function e(e){var n=t.has(e);return e=/^[a-z][.0-9_a-z]*-[\-.0-9_a-z]*$/.test(e),!n&&e}function n(t){var e=t.isConnected;if(void 0!==e)return e;for(;t&&!(t.__CE_isImportDocument||t instanceof Document);)t=t.parentNode||(window.ShadowRoot&&t instanceof ShadowRoot?t.host:void 0);return!(!t||!(t.__CE_isImportDocument||t instanceof Document))}function o(t,e){for(;e&&e!==t&&!e.nextSibling;)e=e.parentNode;return e&&e!==t?e.nextSibling:null}function r(t,e,n){n=void 0===n?new Set:n;for(var i=t;i;){if(i.nodeType===Node.ELEMENT_NODE){var a=i;e(a);var c=a.localName;if("link"===c&&"import"===a.getAttribute("rel")){if((i=a.import)instanceof Node&&!n.has(i))for(n.add(i),i=i.firstChild;i;i=i.nextSibling)r(i,e,n);i=o(t,a);continue}if("template"===c){i=o(t,a);continue}if(a=a.__CE_shadowRoot)for(a=a.firstChild;a;a=a.nextSibling)r(a,e,n)}i=i.firstChild?i.firstChild:o(t,i)}}function i(t,e,n){t[e]=n}function a(){this.a=new Map,this.g=new Map,this.c=[],this.f=[],this.b=!1}function c(t,e){t.b&&r(e,(function(e){return l(t,e)}))}function l(t,e){if(t.b&&!e.__CE_patched){e.__CE_patched=!0;for(var n=0;n<t.c.length;n++)t.c[n](e);for(n=0;n<t.f.length;n++)t.f[n](e)}}function s(t,e){var n=[];for(r(e,(function(t){return n.push(t)})),e=0;e<n.length;e++){var o=n[e];1===o.__CE_state?t.connectedCallback(o):d(t,o)}}function u(t,e){var n=[];for(r(e,(function(t){return n.push(t)})),e=0;e<n.length;e++){var o=n[e];1===o.__CE_state&&t.disconnectedCallback(o)}}function f(t,e,n){var o=(n=void 0===n?{}:n).u||new Set,i=n.i||function(e){return d(t,e)},a=[];if(r(e,(function(e){if("link"===e.localName&&"import"===e.getAttribute("rel")){var n=e.import;n instanceof Node&&(n.__CE_isImportDocument=!0,n.__CE_hasRegistry=!0),n&&"complete"===n.readyState?n.__CE_documentLoadHandled=!0:e.addEventListener("load",(function(){var n=e.import;if(!n.__CE_documentLoadHandled){n.__CE_documentLoadHandled=!0;var r=new Set(o);r.delete(n),f(t,n,{u:r,i:i})}}))}else a.push(e)}),o),t.b)for(e=0;e<a.length;e++)l(t,a[e]);for(e=0;e<a.length;e++)i(a[e])}function d(t,e){if(void 0===e.__CE_state){var o=e.ownerDocument;if((o.defaultView||o.__CE_isImportDocument&&o.__CE_hasRegistry)&&(o=t.a.get(e.localName))){o.constructionStack.push(e);var r=o.constructorFunction;try{try{if(new r!==e)throw Error("The custom element constructor did not produce the element being upgraded.")}finally{o.constructionStack.pop()}}catch(c){throw e.__CE_state=2,c}if(e.__CE_state=1,e.__CE_definition=o,o.attributeChangedCallback)for(o=o.observedAttributes,r=0;r<o.length;r++){var i=o[r],a=e.getAttribute(i);null!==a&&t.attributeChangedCallback(e,i,null,a,null)}n(e)&&t.connectedCallback(e)}}}function p(t){var e=document;this.c=t,this.a=e,this.b=void 0,f(this.c,this.a),"loading"===this.a.readyState&&(this.b=new MutationObserver(this.f.bind(this)),this.b.observe(this.a,{childList:!0,subtree:!0}))}function h(t){t.b&&t.b.disconnect()}function m(){var t=this;this.b=this.a=void 0,this.c=new Promise((function(e){t.b=e,t.a&&e(t.a)}))}function b(t){if(t.a)throw Error("Already resolved.");t.a=void 0,t.b&&t.b(void 0)}function y(t){this.c=!1,this.a=t,this.j=new Map,this.f=function(t){return t()},this.b=!1,this.g=[],this.o=new p(t)}a.prototype.connectedCallback=function(t){var e=t.__CE_definition;e.connectedCallback&&e.connectedCallback.call(t)},a.prototype.disconnectedCallback=function(t){var e=t.__CE_definition;e.disconnectedCallback&&e.disconnectedCallback.call(t)},a.prototype.attributeChangedCallback=function(t,e,n,o,r){var i=t.__CE_definition;i.attributeChangedCallback&&-1<i.observedAttributes.indexOf(e)&&i.attributeChangedCallback.call(t,e,n,o,r)},p.prototype.f=function(t){var e=this.a.readyState;for("interactive"!==e&&"complete"!==e||h(this),e=0;e<t.length;e++)for(var n=t[e].addedNodes,o=0;o<n.length;o++)f(this.c,n[o])},y.prototype.l=function(t,n){var o=this;if(!(n instanceof Function))throw new TypeError("Custom element constructors must be functions.");if(!e(t))throw new SyntaxError("The element name '"+t+"' is not valid.");if(this.a.a.get(t))throw Error("A custom element with name '"+t+"' has already been defined.");if(this.c)throw Error("A custom element is already being defined.");this.c=!0;try{var r=function(t){var e=i[t];if(void 0!==e&&!(e instanceof Function))throw Error("The '"+t+"' callback must be a function.");return e},i=n.prototype;if(!(i instanceof Object))throw new TypeError("The custom element constructor's prototype is not an object.");var a=r("connectedCallback"),c=r("disconnectedCallback"),l=r("adoptedCallback"),s=r("attributeChangedCallback"),u=n.observedAttributes||[]}catch(p){return}finally{this.c=!1}n={localName:t,constructorFunction:n,connectedCallback:a,disconnectedCallback:c,adoptedCallback:l,attributeChangedCallback:s,observedAttributes:u,constructionStack:[]},function(t,e,n){t.a.set(e,n),t.g.set(n.constructorFunction,n)}(this.a,t,n),this.g.push(n),this.b||(this.b=!0,this.f((function(){return function(t){if(!1!==t.b){t.b=!1;for(var e=t.g,n=[],o=new Map,r=0;r<e.length;r++)o.set(e[r].localName,[]);for(f(t.a,document,{i:function(e){if(void 0===e.__CE_state){var r=e.localName,i=o.get(r);i?i.push(e):t.a.a.get(r)&&n.push(e)}}}),r=0;r<n.length;r++)d(t.a,n[r]);for(;0<e.length;){var i=e.shift();r=i.localName,i=o.get(i.localName);for(var a=0;a<i.length;a++)d(t.a,i[a]);(r=t.j.get(r))&&b(r)}}}(o)})))},y.prototype.i=function(t){f(this.a,t)},y.prototype.get=function(t){if(t=this.a.a.get(t))return t.constructorFunction},y.prototype.m=function(t){if(!e(t))return Promise.reject(new SyntaxError("'"+t+"' is not a valid custom element name."));var n=this.j.get(t);return n||(n=new m,this.j.set(t,n),this.a.a.get(t)&&!this.g.some((function(e){return e.localName===t}))&&b(n)),n.c},y.prototype.s=function(t){h(this.o);var e=this.f;this.f=function(n){return t((function(){return e(n)}))}},window.CustomElementRegistry=y,y.prototype.define=y.prototype.l,y.prototype.upgrade=y.prototype.i,y.prototype.get=y.prototype.get,y.prototype.whenDefined=y.prototype.m,y.prototype.polyfillWrapFlushCallback=y.prototype.s;var g=window.Document.prototype.createElement,v=window.Document.prototype.createElementNS,w=window.Document.prototype.importNode,E=window.Document.prototype.prepend,C=window.Document.prototype.append,_=window.DocumentFragment.prototype.prepend,N=window.DocumentFragment.prototype.append,A=window.Node.prototype.cloneNode,S=window.Node.prototype.appendChild,T=window.Node.prototype.insertBefore,D=window.Node.prototype.removeChild,L=window.Node.prototype.replaceChild,M=Object.getOwnPropertyDescriptor(window.Node.prototype,"textContent"),k=window.Element.prototype.attachShadow,x=Object.getOwnPropertyDescriptor(window.Element.prototype,"innerHTML"),O=window.Element.prototype.getAttribute,j=window.Element.prototype.setAttribute,F=window.Element.prototype.removeAttribute,H=window.Element.prototype.getAttributeNS,R=window.Element.prototype.setAttributeNS,P=window.Element.prototype.removeAttributeNS,I=window.Element.prototype.insertAdjacentElement,U=window.Element.prototype.insertAdjacentHTML,B=window.Element.prototype.prepend,z=window.Element.prototype.append,K=window.Element.prototype.before,W=window.Element.prototype.after,Y=window.Element.prototype.replaceWith,q=window.Element.prototype.remove,V=window.HTMLElement,X=Object.getOwnPropertyDescriptor(window.HTMLElement.prototype,"innerHTML"),$=window.HTMLElement.prototype.insertAdjacentElement,G=window.HTMLElement.prototype.insertAdjacentHTML,J=new function(){};function Q(t,e,o){function r(e){return function(o){for(var r=[],i=0;i<arguments.length;++i)r[i]=arguments[i];i=[];for(var a=[],c=0;c<r.length;c++){var l=r[c];if(l instanceof Element&&n(l)&&a.push(l),l instanceof DocumentFragment)for(l=l.firstChild;l;l=l.nextSibling)i.push(l);else i.push(l)}for(e.apply(this,r),r=0;r<a.length;r++)u(t,a[r]);if(n(this))for(r=0;r<i.length;r++)(a=i[r])instanceof Element&&s(t,a)}}void 0!==o.h&&(e.prepend=r(o.h)),void 0!==o.append&&(e.append=r(o.append))}var Z,tt=window.customElements;if(!tt||tt.forcePolyfill||"function"!=typeof tt.define||"function"!=typeof tt.get){var et=new a;Z=et,window.HTMLElement=function(){function t(){var t=this.constructor,e=Z.g.get(t);if(!e)throw Error("The custom element being constructed was not registered with \`customElements\`.");var n=e.constructionStack;if(0===n.length)return n=g.call(document,e.localName),Object.setPrototypeOf(n,t.prototype),n.__CE_state=1,n.__CE_definition=e,l(Z,n),n;var o=n[e=n.length-1];if(o===J)throw Error("The HTMLElement constructor was either called reentrantly for this constructor or called multiple times.");return n[e]=J,Object.setPrototypeOf(o,t.prototype),l(Z,o),o}return t.prototype=V.prototype,Object.defineProperty(t.prototype,"constructor",{writable:!0,configurable:!0,enumerable:!1,value:t}),t}(),function(){var t=et;i(Document.prototype,"createElement",(function(e){if(this.__CE_hasRegistry){var n=t.a.get(e);if(n)return new n.constructorFunction}return e=g.call(this,e),l(t,e),e})),i(Document.prototype,"importNode",(function(e,n){return e=w.call(this,e,!!n),this.__CE_hasRegistry?f(t,e):c(t,e),e})),i(Document.prototype,"createElementNS",(function(e,n){if(this.__CE_hasRegistry&&(null===e||"http://www.w3.org/1999/xhtml"===e)){var o=t.a.get(n);if(o)return new o.constructorFunction}return e=v.call(this,e,n),l(t,e),e})),Q(t,Document.prototype,{h:E,append:C})}(),Q(et,DocumentFragment.prototype,{h:_,append:N}),function(){function t(t,o){Object.defineProperty(t,"textContent",{enumerable:o.enumerable,configurable:!0,get:o.get,set:function(t){if(this.nodeType===Node.TEXT_NODE)o.set.call(this,t);else{var r=void 0;if(this.firstChild){var i=this.childNodes,a=i.length;if(0<a&&n(this)){r=Array(a);for(var c=0;c<a;c++)r[c]=i[c]}}if(o.set.call(this,t),r)for(t=0;t<r.length;t++)u(e,r[t])}}})}var e=et;i(Node.prototype,"insertBefore",(function(t,o){if(t instanceof DocumentFragment){var r=Array.prototype.slice.apply(t.childNodes);if(t=T.call(this,t,o),n(this))for(o=0;o<r.length;o++)s(e,r[o]);return t}return r=n(t),o=T.call(this,t,o),r&&u(e,t),n(this)&&s(e,t),o})),i(Node.prototype,"appendChild",(function(t){if(t instanceof DocumentFragment){var o=Array.prototype.slice.apply(t.childNodes);if(t=S.call(this,t),n(this))for(var r=0;r<o.length;r++)s(e,o[r]);return t}return o=n(t),r=S.call(this,t),o&&u(e,t),n(this)&&s(e,t),r})),i(Node.prototype,"cloneNode",(function(t){return t=A.call(this,!!t),this.ownerDocument.__CE_hasRegistry?f(e,t):c(e,t),t})),i(Node.prototype,"removeChild",(function(t){var o=n(t),r=D.call(this,t);return o&&u(e,t),r})),i(Node.prototype,"replaceChild",(function(t,o){if(t instanceof DocumentFragment){var r=Array.prototype.slice.apply(t.childNodes);if(t=L.call(this,t,o),n(this))for(u(e,o),o=0;o<r.length;o++)s(e,r[o]);return t}r=n(t);var i=L.call(this,t,o),a=n(this);return a&&u(e,o),r&&u(e,t),a&&s(e,t),i})),M&&M.get?t(Node.prototype,M):function(t,e){t.b=!0,t.c.push(e)}(e,(function(e){t(e,{enumerable:!0,configurable:!0,get:function(){for(var t=[],e=0;e<this.childNodes.length;e++){var n=this.childNodes[e];n.nodeType!==Node.COMMENT_NODE&&t.push(n.textContent)}return t.join("")},set:function(t){for(;this.firstChild;)D.call(this,this.firstChild);null!=t&&""!==t&&S.call(this,document.createTextNode(t))}})}))}(),function(){function t(t,e){Object.defineProperty(t,"innerHTML",{enumerable:e.enumerable,configurable:!0,get:e.get,set:function(t){var o=this,i=void 0;if(n(this)&&(i=[],r(this,(function(t){t!==o&&i.push(t)}))),e.set.call(this,t),i)for(var l=0;l<i.length;l++){var s=i[l];1===s.__CE_state&&a.disconnectedCallback(s)}return this.ownerDocument.__CE_hasRegistry?f(a,this):c(a,this),t}})}function e(t,e){i(t,"insertAdjacentElement",(function(t,o){var r=n(o);return t=e.call(this,t,o),r&&u(a,o),n(t)&&s(a,o),t}))}function o(t,e){function n(t,e){for(var n=[];t!==e;t=t.nextSibling)n.push(t);for(e=0;e<n.length;e++)f(a,n[e])}i(t,"insertAdjacentHTML",(function(t,o){if("beforebegin"===(t=t.toLowerCase())){var r=this.previousSibling;e.call(this,t,o),n(r||this.parentNode.firstChild,this)}else if("afterbegin"===t)r=this.firstChild,e.call(this,t,o),n(this.firstChild,r);else if("beforeend"===t)r=this.lastChild,e.call(this,t,o),n(r||this.firstChild,null);else{if("afterend"!==t)throw new SyntaxError("The value provided ("+String(t)+") is not one of 'beforebegin', 'afterbegin', 'beforeend', or 'afterend'.");r=this.nextSibling,e.call(this,t,o),n(this.nextSibling,r)}}))}var a=et;k&&i(Element.prototype,"attachShadow",(function(t){t=k.call(this,t);var e=a;if(e.b&&!t.__CE_patched){t.__CE_patched=!0;for(var n=0;n<e.c.length;n++)e.c[n](t)}return this.__CE_shadowRoot=t})),x&&x.get?t(Element.prototype,x):X&&X.get?t(HTMLElement.prototype,X):function(t,e){t.b=!0,t.f.push(e)}(a,(function(e){t(e,{enumerable:!0,configurable:!0,get:function(){return A.call(this,!0).innerHTML},set:function(t){var e="template"===this.localName,n=e?this.content:this,o=v.call(document,this.namespaceURI,this.localName);for(o.innerHTML=t;0<n.childNodes.length;)D.call(n,n.childNodes[0]);for(t=e?o.content:o;0<t.childNodes.length;)S.call(n,t.childNodes[0])}})})),i(Element.prototype,"setAttribute",(function(t,e){if(1!==this.__CE_state)return j.call(this,t,e);var n=O.call(this,t);j.call(this,t,e),e=O.call(this,t),a.attributeChangedCallback(this,t,n,e,null)})),i(Element.prototype,"setAttributeNS",(function(t,e,n){if(1!==this.__CE_state)return R.call(this,t,e,n);var o=H.call(this,t,e);R.call(this,t,e,n),n=H.call(this,t,e),a.attributeChangedCallback(this,e,o,n,t)})),i(Element.prototype,"removeAttribute",(function(t){if(1!==this.__CE_state)return F.call(this,t);var e=O.call(this,t);F.call(this,t),null!==e&&a.attributeChangedCallback(this,t,e,null,null)})),i(Element.prototype,"removeAttributeNS",(function(t,e){if(1!==this.__CE_state)return P.call(this,t,e);var n=H.call(this,t,e);P.call(this,t,e);var o=H.call(this,t,e);n!==o&&a.attributeChangedCallback(this,e,n,o,t)})),$?e(HTMLElement.prototype,$):I?e(Element.prototype,I):console.warn("Custom Elements: \`Element#insertAdjacentElement\` was not patched."),G?o(HTMLElement.prototype,G):U?o(Element.prototype,U):console.warn("Custom Elements: \`Element#insertAdjacentHTML\` was not patched."),Q(a,Element.prototype,{h:B,append:z}),function(t){function e(e){return function(o){for(var r=[],i=0;i<arguments.length;++i)r[i]=arguments[i];i=[];for(var a=[],c=0;c<r.length;c++){var l=r[c];if(l instanceof Element&&n(l)&&a.push(l),l instanceof DocumentFragment)for(l=l.firstChild;l;l=l.nextSibling)i.push(l);else i.push(l)}for(e.apply(this,r),r=0;r<a.length;r++)u(t,a[r]);if(n(this))for(r=0;r<i.length;r++)(a=i[r])instanceof Element&&s(t,a)}}var o=Element.prototype;void 0!==K&&(o.before=e(K)),void 0!==K&&(o.after=e(W)),void 0!==Y&&i(o,"replaceWith",(function(e){for(var o=[],r=0;r<arguments.length;++r)o[r]=arguments[r];r=[];for(var i=[],a=0;a<o.length;a++){var c=o[a];if(c instanceof Element&&n(c)&&i.push(c),c instanceof DocumentFragment)for(c=c.firstChild;c;c=c.nextSibling)r.push(c);else r.push(c)}for(a=n(this),Y.apply(this,o),o=0;o<i.length;o++)u(t,i[o]);if(a)for(u(t,this),o=0;o<r.length;o++)(i=r[o])instanceof Element&&s(t,i)})),void 0!==q&&i(o,"remove",(function(){var e=n(this);q.call(this),e&&u(t,this)}))}(a)}(),document.__CE_hasRegistry=!0;var nt=new y(et);Object.defineProperty(window,"customElements",{configurable:!0,enumerable:!0,value:nt})}}).call(self);`;