Added CONSTANT VIGILANCE feature

src/contentScript.js

 	return shouldKillSticky;
 }
 
+/*	Some websites add sticky elements after loading, or make existing elements
+	sticky (either on a timer, or based on user actions). CONSTANT VIGILANCE
+	counteracts this behavior, by watching the DOM for mutations, and, if
+	necessary, killing any newly-formed stickies.
+	*/
+function startConstantVigilance() {
+	var observer = new MutationObserver((mutationsList, observer) => {
+		var shouldKillSticky = false;
+		for (var mutation of mutationsList) {
+			if (mutation.target.style.position == 'fixed' ||
+				mutation.target.style.position == 'sticky')
+				shouldKillSticky = true;
+		}
+		if (shouldKillSticky)
+			requestAnimationFrame(() => { killSticky(); });
+	});
+
+	observer.observe(document.querySelector("body"), {
+		attributes: true, 
+		childList: true, 
+		subtree: true
+	});
+}
+
 /******************/
 /* INITIALIZATION */
 /******************/
 
 function initialize() {
-	chrome.storage.sync.get([ "matchingPatterns", "exclusionPatterns", "mode" ],
+	chrome.storage.sync.get([ "matchingPatterns", "exclusionPatterns", "mode", "constantVigilance" ],
 	(result) => {
 		let shouldKillSticky = checkForShouldKillSticky(result);
 		updateIcon(shouldKillSticky);
+		let constantVigilance = (result.constantVigilance == "false") ? false : true;
 		window.onload = () => {
-			if (shouldKillSticky) killSticky();
+			if (shouldKillSticky) {
+				killSticky();
+				if (constantVigilance) startConstantVigilance();
+			}
 		};
 	});
 }

src/options.css

 	display: flex;
 	flex-flow: row wrap;
 	align-items: center;
-	max-width: 640px;
+	max-width: 750px;
 }
 .top-controls .buttons {
 	display: flex;
 	background-color: #777;
 	opacity: 0.3;
 }
+.top-controls button:not(:disabled):hover {
+	text-shadow:
+		0 0 1px #fff,
+		0 0 3px #fff,
+		0 0 5px #fff;
+	cursor: pointer;
+}
+
+/******************/
+/* MODE SELECTION */
+/******************/
+
 input#whitelist-mode {
 	display: block;
 	-webkit-appearance: none;
 	align-self: flex-start;
 	border: 1px solid #ddd;
 	padding: 8px 10px;
+	margin
 	cursor: default;
 	background-color: #fff;
 }
 .mode-select-container span:not(.disabled):hover {
 	border-bottom: 1px solid currentColor;
 }
-.top-controls button:not(:disabled):hover {
-	text-shadow:
-		0 0 1px #fff,
-		0 0 3px #fff,
-		0 0 5px #fff;
+
+/**********************/
+/* CONSTANT VIGILANCE */
+/**********************/
+
+.constant-vigilance-container {
+	border: 1px solid #ddd;
+	padding: 9px 13px 12px 11px;
+	display: flex;
+	align-items: center;
+	margin: 0 0 0 10px;
+}
+
+.constant-vigilance-container input[type='checkbox'] {
+	-webkit-appearance: none;
+	-moz-appearance: none;
+	border: 1px solid #000;
+	width: 15px;
+	height: 15px;
+	position: relative;
+	top: 1px;
+	margin: 3px 5px 0 0;
+}
+.constant-vigilance-container input[type='checkbox'],
+.constant-vigilance-container label {
 	cursor: pointer;
 }
-p.note {
-	font-size: 0.875em;
+.constant-vigilance-container label {
+	line-height: 1;
+	padding: 8px 0 0 0;
+	border-bottom: 1px solid transparent;
+	font-size: 0.875rem;
+}
+.constant-vigilance-container label::selection {
+	background-color: transparent;
+}
+.constant-vigilance-container input[type='checkbox']:focus {
+	outline: none;
+}
+.constant-vigilance-container input[type='checkbox']:focus + label,
+.constant-vigilance-container input[type='checkbox']:hover + label,
+.constant-vigilance-container input[type='checkbox'] + label:hover {
+	border-bottom: 1px dotted #000;
+}
+.constant-vigilance-container input[type='checkbox']:checked,
+.constant-vigilance-container input[type='checkbox']:hover {
+	box-shadow: 0 0 0 2px #fff inset;
+}
+.constant-vigilance-container input[type='checkbox']:hover {
+	background-color: #ccc;
+}
+.constant-vigilance-container input[type='checkbox']:checked {
+	background-color: #000;
 }
 
 /******************/
 .fa-heavy {
 	font-weight: 900;
 }
+p.note {
+	font-size: 0.875em;
+}

src/options.html

 			<input type='checkbox' id='whitelist-mode'></input>
 			<span class='whitelist-mode-label'>Whitelist mode</span>
 		</span>
+		<span class='constant-vigilance-container'>
+			<input type='checkbox' name='constant-vigilance' id='constant-vigilance' checked></input>
+			<label for='constant-vigilance' title='Continue monitoring the page for sticky elements added after page load. (See help for more info.)'>CONSTANT VIGILANCE!</label>
+		</span>
 		<span class='buttons'>
 			<button disabled type='button' class='reset-button'>Reset</button>
 			<button disabled type='button' class='save-button'>Save</button>

src/options.js

 	let matchingPatterns = document.querySelector("#matchingPatterns textarea").value;
 	let exclusionPatterns = document.querySelector("#exclusionPatterns textarea").value;
 	let mode = document.querySelector("input#whitelist-mode").checked ? "whitelist" : "blacklist";
+	let constantVigilance = document.querySelector("input#constant-vigilance").checked ? "true" : "false";
 	chrome.storage.sync.set({
 		"matchingPatterns": matchingPatterns,
 		"exclusionPatterns": exclusionPatterns,
-		"mode": mode
+		"mode": mode,
+		"constantVigilance": constantVigilance
 	}, () => { setButtonsActive(false); });
 }
 
 	discarding the user's changes.
 	*/
 function resetChanges(callback) {
-	chrome.storage.sync.get([ "matchingPatterns", "exclusionPatterns", "mode" ], (result) => {
+	chrome.storage.sync.get([ "matchingPatterns", "exclusionPatterns", "mode", "constantVigilance" ], (result) => {
 		AKS.matchingPatterns = result.matchingPatterns || "";
 		AKS.exclusionPatterns = result.exclusionPatterns || ""
 		AKS.mode = result.mode || "blacklist";
+		AKS.constantVigilance = result.constantVigilance || "true";
 
 		document.querySelector("#matchingPatterns textarea").value = AKS.matchingPatterns;
 		document.querySelector("#exclusionPatterns textarea").value = AKS.exclusionPatterns;
 
 		toggleModeSelectorState(AKS.mode);
 
+		// Set CONSTANT VIGILANCE! checkbox state.
+		document.querySelector("input#constant-vigilance").checked = AKS.constantVigilance == "true";
+
 		// De-activate the "Reset" and "Save" buttons.
 		setButtonsActive(false);
 
 	});
 
 	// Listeners for mode select switch.
-	document.querySelector("input[type='checkbox']").addEventListener("change", (event) => {
+	document.querySelector("input#whitelist-mode").addEventListener("change", (event) => {
 		modeSelectorInputReceived();
 	});
 	document.querySelectorAll(".mode-select-container span").forEach(span => {
 		});
 	});
 
+	/*	Listener to activate Reset/Save buttons when the CONSTANT VIGILANCE
+		checkbox is toggled. */
+	document.querySelector("input#constant-vigilance").addEventListener("change", (event) => {
+		setButtonsActive(true);
+	});
+
 	// Listener for open help button.
 	document.querySelector(".open-help-button").addActivateEvent((event) => {
 		setHelpOverlayVisible(true);