…
    Actors: class {
        constructor(win) {
            this.bc = win.gBrowser.selectedBrowser.browsingContext;
        }
        get actor() {
            return Object.defineProperty(this, "actor", {
                value: this.bc.currentWindowGlobal.getActor("ATBWinActor")
            }).actor;
        }
        *[Symbol.iterator]() {
            yield this.actor;
            var contextsToVisit = Array.from(this.bc.children);
            while (contextsToVisit.length) {
                let currentContext = contextsToVisit.pop();
                let global = currentContext?.currentWindowGlobal;
                if (global)
                    contextsToVisit.push(...currentContext.children),
                    yield global.getActor("ATBWinActor");
            }
        }
    },
    get useBC() {
        delete this.useBC;
        return this.useBC = Cu.getGlobalForObject(Cu)
            .BrowsingContext.prototype.hasOwnProperty("allowJavascript");
    },
    async _sendAsyncMessages(win, message) {
        var actors = new this.Actors(win);
        switch (message) {
            case "ATBWinActor:ScrollPageUp":
            case "ATBWinActor:ScrollPageDown":
            case "ATBWinActor:ScrollTop":
            case "ATBWinActor:ScrollBottom":
                return actors.actor.sendAsyncMessage(message);

            case "ATBWinActor:TextToLink":
                for(var actor of actors)
                    actor.sendAsyncMessage(message);
                return;
            case "ATBWinActor:CopyAllLinks":
                var links = "", count = 0;
                for(var actor of actors) {
                    var data = await actor.sendQuery(message);
                    if (data)
                        links += `${data.links}\n`,
                        count += data.count;
                }
                this.clipboardHelp.copyString(links);
                win.setTimeout(() =>
                    this.showAlert("Копирование ссылок", `${count} ссылок в буфере обмена!`)
                , 100);
                return;

            case "ATBWinActor:PageJavaScript":
                if (this.useBC) {
                    var state = !actors.bc.allowJavascript;
                    for(var bc of actors.bc.getAllBrowsingContextsInSubtree())
                        bc.allowJavascript = state;
                    return;
                }
                var check, getstate = "ATBWinActor:getPageJavaScript"; break;
            case "ATBWinActor:PageImages":
                var check = true, getstate = "ATBWinActor:getPageImages"; break;
            case "ATBWinActor:LinkPointerEvents":
                var check, getstate = "ATBWinActor:getLinkPointerEvents"; break;
            default:
                return;
        }
        var data = {state: !(await actors.actor.sendQuery(getstate))};
        for(var actor of actors)
            await actor.sendQuery(message, data);
        check && this.checkBrowserReload(win);
    },

Services.search.getEnginesByExtensionID("yandex@search.mozilla.org").then(engine => {
    if (!engine.length) return;
    engine[0]._iconURI = Services.io.newURI("chrome://user_chrome_files/content/custom_styles/svg/yandex-ru.ico");
});

menu > menupopup {
	margin-top: -1px !important;
}

(async (searchSelect, popup) => (popup = 
	searchSelect.closest("menupopup")).addEventListener("popupshowing", {

	topic: "browser-search-engine-modified",
	defaultImg: "chrome://browser/skin/search-engine-placeholder.png",
	handleEvent(e) {
		if (searchSelect.hidden) return;

		var menu = document.createXULElement("menu");
		menu.className = "menu-iconic";
		menu.ePopup = menu.appendChild(document.createXULElement("menupopup"));
		menu.onclick = this.search;
		searchSelect.collapsed = true;
		searchSelect.before(menu);

		addEventListener("unload", () => {
			popup.removeEventListener("popupshowing", this);
			this.handleEvent == this.handler &&
				Services.obs.removeObserver(this, this.topic);
		}, {once: true});

		this.handler = () => menu.hidden = searchSelect.hidden;
		this.handlerRebuild = () => this.handler() || this.rebuild(menu);
		this.rebuild(menu);
	},
	async rebuild(menu) {
		var de = Services.search.defaultEngine;
		de = de.wrappedJSObject || de;
		this.setAttrs(menu, de, `Искать в ${de.name} или в ...`);
		menu.ePopup.textContent = "";
		for(var engine of await Services.search.getVisibleEngines()) {
			if (engine == de) continue;
			var menuitem = document.createXULElement("menuitem");
			menuitem.className = "menuitem-iconic";
			this.setAttrs(menuitem, engine);
			menu.ePopup.append(menuitem);
		}
		this.handleEvent = this.handler;
		Services.obs.addObserver(this, this.topic, false);
	},
	setAttrs(node, engine, label = engine.name) {
		node.engine = engine;
		node.setAttribute("label", label);
		node.setAttribute("image", engine.iconURI ? engine.iconURI.spec : this.defaultImg);
	},
	observe() {
		this.handleEvent = this.handlerRebuild;
		Services.obs.removeObserver(this, this.topic);
	},
	search(e) {
		var {engine} = e.target;
		if (!engine) return;
		var submission = engine.getSubmission(
			searchSelect.searchTerms, null, "contextmenu"
		);
		submission && openLinkIn(submission.uri.spec, "tab", {
			postData: submission.postData,
			inBackground: e.button > 0,
			relatedToCurrent: true,
			triggeringPrincipal: searchSelect.principal
		});
		e.button != 1 && popup.state == "open" && popup.hidePopup();
	}
}))(document.getElementById("context-searchselect"));

:root {
	--arrowpanel-menuitem-padding-block: 2px !important;
	--panel-separator-margin: 3px 8px !important;
	--panel-subview-body-padding: 6px 0 !important;
}