Rocket.Chat/packages/rocketchat-message-snippet/client/tabBar/tabBar.js

Meteor.startup(function() {
	Tracker.autorun(function() {
		if (RocketChat.settings.get("Message_AllowSnippeting")) {
			RocketChat.TabBar.addButton({
				groups: ["channel", "privategroup", "directmessages"],
				id: "snippeted-messages",
				i18nTitle: 'Snippeted_Messages',
				icon: 'icon-code',
				template: 'snippetedMessages',
				order: 20
			});
		} else {
			RocketChat.TabBar.removeButton("snippeted-messages");
		}
	});
});