diff --git a/controllers/EditAsset.php b/controllers/EditAsset.php
index f3ee61b..8fc7bf4 100644
--- a/controllers/EditAsset.php
+++ b/controllers/EditAsset.php
@@ -116,18 +116,25 @@ class EditAsset extends HTMLController
 			if (!preg_match('~^(?<width>\d+)x(?<height>\d+)(?<suffix>_c(?<method>[best]?))?$~', $selector, $thumb))
 				continue;
 
-			$has_crop_boundary = isset($metadata['crop_' . $thumb['width'] . 'x' . $thumb['height']]);
-			$has_custom_image = isset($metadata['custom_' . $thumb['width'] . 'x' . $thumb['height']]);
+			$dimensions = $thumb['width'] . 'x' . $thumb['height'];
+
+			// Does the thumbnail exist on disk? If not, use an url to generate it.
+			if (!$filename || !file_exists(THUMBSDIR . '/' . $subdir . '/' . $filename))
+				$thumb_url = BASEURL . '/thumbnail/' . $image->getId() . '/' . $dimensions . ($thumb['suffix'] ?? '') . '/';
+			else
+				$thumb_url = THUMBSURL . '/' . $subdir . '/' . $filename;
+
+			$has_crop_boundary = isset($metadata['crop_' . $dimensions]);
+			$has_custom_image = isset($metadata['custom_' . $dimensions]);
+
 			$thumbs[] = [
 				'dimensions' => [(int) $thumb['width'], (int) $thumb['height']],
 				'cropped' => !$has_custom_image && (!empty($thumb['suffix']) || $has_crop_boundary),
 				'crop_method' => !$has_custom_image && !empty($thumb['method']) ? $thumb['method'] : (!empty($thumb['suffix']) ? 'c' : null),
-				'crop_region' => $has_crop_boundary ? $metadata['crop_' . $thumb['width'] . 'x' . $thumb['height']] : null,
+				'crop_region' => $has_crop_boundary ? $metadata['crop_' . $dimensions] : null,
 				'custom_image' => $has_custom_image,
 				'filename' => $filename,
-				'full_path' => THUMBSDIR . '/' . $subdir . '/' . $filename,
-				'url' => THUMBSURL . '/' . $subdir . '/' . $filename,
-				'status' => file_exists(THUMBSDIR . '/' . $subdir . '/' . $filename),
+				'url' => $thumb_url,
 			];
 		}
 
@@ -144,18 +151,19 @@ class EditAsset extends HTMLController
 		$crop_value = $data->crop_width . ',' . $data->crop_height . ',' . $data->source_x . ',' . $data->source_y;
 		$meta[$crop_key] = $crop_value;
 
-		// If we uploaded a custom thumbnail, stop considering it such.
+		// If we previously uploaded a custom thumbnail, stop considering it such.
 		$custom_key = 'custom_' . $data->thumb_width . 'x' . $data->thumb_height;
 		if (isset($meta[$custom_key]))
+		{
+			// TODO: delete from disk
 			unset($meta[$custom_key]);
+		}
+
+		// Save meta changes so far.
+		$image->setMetaData($meta);
 
 		// Force a rebuild of related thumbnails.
-		$thumb_key = 'thumb_' . $data->thumb_width . 'x' . $data->thumb_height;
-		foreach ($meta as $meta_key => $meta_value)
-			if ($meta_key === $thumb_key || strpos($meta_key, $thumb_key . '_') !== false)
-				unset($meta[$meta_key]);
-
-		$image->setMetaData($meta);
+		$image->removeThumbnailsOfSize($data->thumb_width, $data->thumb_height);
 
 		$payload = [
 			'key' => $crop_key,
diff --git a/models/Image.php b/models/Image.php
index dae6422..c8205f8 100644
--- a/models/Image.php
+++ b/models/Image.php
@@ -133,9 +133,9 @@ class Image extends Asset
 
 	public function removeAllThumbnails()
 	{
-		foreach ($this->thumbnails as $key => $value)
+		foreach ($this->thumbnails as $key => $filename)
 		{
-			$thumb_path = THUMBSDIR . '/' . $this->subdir . '/' . $value;
+			$thumb_path = THUMBSDIR . '/' . $this->subdir . '/' . $filename;
 			if (is_file($thumb_path))
 				unlink($thumb_path);
 		}
@@ -146,6 +146,30 @@ class Image extends Asset
 			['id_asset' => $this->id_asset]);
 	}
 
+	public function removeThumbnailsOfSize($width, $height)
+	{
+		foreach ($this->thumbnails as $key => $filename)
+		{
+			if (strpos($key, $width . 'x' . $height) !== 0)
+				continue;
+
+			$thumb_path = THUMBSDIR . '/' . $this->subdir . '/' . $filename;
+			if (is_file($thumb_path))
+				unlink($thumb_path);
+		}
+
+		return Registry::get('db')->query('
+			DELETE FROM assets_thumbs
+			WHERE id_asset = {int:id_asset} AND
+				width = {int:width} AND
+				height = {int:height}',
+			[
+				'height' => $height,
+				'id_asset' => $this->id_asset,
+				'width' => $width,
+			]);
+	}
+
 	public function replaceThumbnail($descriptor, $tmp_file)
 	{
 		if (!is_file($tmp_file))
diff --git a/models/Thumbnail.php b/models/Thumbnail.php
index 2298735..46eda45 100644
--- a/models/Thumbnail.php
+++ b/models/Thumbnail.php
@@ -164,6 +164,8 @@ class Thumbnail
 				$this->filename_suffix .= 's';
 			elseif ($this->crop_mode === self::CROP_MODE_SLICE_BOTTOM)
 				$this->filename_suffix .= 'b';
+			elseif ($this->crop_mode === self::CROP_MODE_BOUNDARY)
+				$this->filename_suffix .= 'e';
 		}
 		else
 			$this->filename_suffix = '';
diff --git a/public/css/admin.css b/public/css/admin.css
index 4e58d3e..f3f3b90 100644
--- a/public/css/admin.css
+++ b/public/css/admin.css
@@ -145,46 +145,55 @@ body {
 /* Crop editor
 ----------------*/
 #crop_editor {
+	display: flex;
+	flex-direction: column;
 	position: fixed;
 	top: 0;
 	left: 0;
 	height: 100%;
 	width: 100%;
-	background: #000;
+	background: rgba(0, 0, 0, 0.8);
 	z-index: 100;
 	color: #fff;
 }
-#crop_editor input {
+#crop_editor input[type=number] {
 	width: 50px;
 	background: #555;
 	color: #fff;
 }
-.crop_image_container {
-	position: relative;
+#crop_editor input[type=checkbox] {
+	vertical-align: middle;
 }
 .crop_position {
+	background: rgba(0, 0, 0, 1.0);
+	border: none;
 	padding: 5px;
 	text-align: center;
 }
 .crop_position input, .crop_position .btn {
 	margin: 0 5px;
 }
+
+.crop_image_container {
+	position: relative;
+	flex-grow: 1;
+	max-height: calc(100% - 34px);
+}
 .crop_image_container img {
-	height: auto;
-	width: auto;
+	border: 1px solid #000;
+	max-height: 100%;
 	max-width: 100%;
-	max-height: 700px;
 }
 #crop_boundary {
-	border: 1px solid rgba(255, 255, 255, 0.75);
-	background: rgba(255, 255, 255, 0.75);
+	border: 1px dashed rgb(255, 255, 255);
+	background: rgba(255, 255, 255, 0.4);
+	cursor: move;
 	position: absolute;
 	z-index: 200;
 	width: 500px;
 	height: 300px;
 	top: 400px;
 	left: 300px;
-	filter: invert(100%); /* temp */
 }
 
 
diff --git a/public/css/default.css b/public/css/default.css
index 861d257..020da75 100644
--- a/public/css/default.css
+++ b/public/css/default.css
@@ -375,34 +375,59 @@ footer a {
 
 input, select, .btn {
 	background: #fff;
-	border: 1px solid #ccc;
+	border: 1px solid #dbdbdb;
+	border-radius: 4px;
 	color: #000;
 	font: 13px/1.7 "Open Sans", "Helvetica", sans-serif;
 	padding: 3px;
 }
-input[type=submit], button, .btn {
-	background: #ddd;
-	border-radius: 3px;
-	border: 1px solid #aaa;
-	display: inline-block;
-	font: inherit;
-	padding: 4px 5px;
-}
-input[type=submit]:hover, button:hover, .btn:hover {
-	background-color: #d0d0d0;
-	border-color: #a0a0a0;
-}
 textarea {
-	border: 1px solid #ccc;
-	font: 12px/1.4 'Monaco', 'Inconsolata', 'DejaVu Sans Mono', monospace;
+	border: 1px solid #dbdbdb;
+	border-radius: 4px;
+	font: 14px/1.4 'Inconsolata', 'DejaVu Sans Mono', monospace;
 	padding: 0.75%;
-	width: 98.5%;
 }
+
+input[type=submit], button, .btn {
+	background-color: #eee;
+	border-color: #dbdbdb;
+	border-width: 1px;
+	border-radius: 4px;
+	color: #363636;
+	cursor: pointer;
+	display: inline-block;
+	justify-content: center;
+	padding-bottom: calc(0.4em - 1px);
+	padding-left: 0.8em;
+	padding-right: 0.8em;
+	padding-top: calc(0.4em - 1px);
+	text-align: center;
+	white-space: nowrap;
+}
+input:hover, select:hover, button:hover, .btn:hover {
+	border-color: #b5b5b5;
+}
+input:focus, select:focus, button:focus, .btn:focus {
+	border-color: #3273dc;
+}
+input:focus:not(:active), select:focus:not(:active), button:focus:not(:active), .btn:focus:not(:active) {
+	box-shadow: 0px 0px 0px 2px rgba(50, 115, 220, 0.25);
+}
+input:active, select:active, button:active, .btn:active {
+	border-color: #4a4a4a;
+}
+
 .btn-red {
-	background: #F3B076;
-	border-color: #C98245;
+	background: #eebbaa;
+	border-color: #cc9988;
+}
+.btn-red:hover, .btn-red:focus {
+	border-color: #bb7766;
 	color: #000;
 }
+.btn-red:focus:not(:active) {
+	box-shadow: 0px 0px 0px 2px rgba(241, 70, 104, 0.25);
+}
 
 
 /* Login box styles
diff --git a/public/js/crop_editor.js b/public/js/crop_editor.js
index e010d03..555ec83 100644
--- a/public/js/crop_editor.js
+++ b/public/js/crop_editor.js
@@ -1,218 +1,374 @@
-function CropEditor(opt) {
-	this.opt = opt;
+class CropEditor {
+	constructor(opt) {
+		this.opt = opt;
 
-	this.edit_crop_button = document.createElement("span");
-	this.edit_crop_button.className = "btn";
-	this.edit_crop_button.innerHTML = "Edit crop";
-	this.edit_crop_button.addEventListener('click', this.show.bind(this));
+		this.edit_crop_button = document.createElement("span");
+		this.edit_crop_button.className = "btn";
+		this.edit_crop_button.textContent = "Edit crop";
+		this.edit_crop_button.addEventListener('click', this.show.bind(this));
 
-	this.thumbnail_select = document.getElementById(opt.thumbnail_select_id);
-	this.thumbnail_select.addEventListener('change', this.toggleCropButton.bind(this));
-	this.thumbnail_select.parentNode.insertBefore(this.edit_crop_button, this.thumbnail_select.nextSibling);
+		this.thumbnail_select = document.getElementById(opt.thumbnail_select_id);
+		this.thumbnail_select.addEventListener('change', this.toggleCropButton.bind(this));
+		this.thumbnail_select.parentNode.insertBefore(this.edit_crop_button, this.thumbnail_select.nextSibling);
 
-	this.toggleCropButton();
-}
+		this.toggleCropButton();
+	}
 
-CropEditor.prototype.buildContainer = function() {
-	this.container = document.createElement("div");
-	this.container.id = "crop_editor";
+	initDOM() {
+		this.container = document.createElement("div");
+		this.container.id = "crop_editor";
 
-	this.position = document.createElement("div");
-	this.position.className = "crop_position";
-	this.container.appendChild(this.position);
+		this.initPositionForm();
+		this.initImageContainer();
 
-	var source_x_label = document.createTextNode("Source X:");
-	this.position.appendChild(source_x_label);
+		this.parent = document.getElementById(this.opt.editor_container_parent_id);
+		this.parent.appendChild(this.container);
+	}
 
-	this.source_x = document.createElement("input");
-	this.source_x.addEventListener("keyup", this.positionBoundary.bind(this));
-	this.position.appendChild(this.source_x);
+	initPositionForm() {
+		this.position = document.createElement("fieldset");
+		this.position.className = "crop_position";
+		this.container.appendChild(this.position);
 
-	var source_y_label = document.createTextNode("Source Y:");
-	this.position.appendChild(source_y_label);
+		let source_x_label = document.createTextNode("Source X:");
+		this.position.appendChild(source_x_label);
 
-	this.source_y = document.createElement("input");
-	this.source_y.addEventListener("keyup", this.positionBoundary.bind(this));
-	this.position.appendChild(this.source_y);
+		this.source_x = document.createElement("input");
+		this.source_x.type = 'number';
+		this.source_x.addEventListener("change", this.positionBoundary.bind(this));
+		this.source_x.addEventListener("keyup", this.positionBoundary.bind(this));
+		this.position.appendChild(this.source_x);
 
-	var crop_width_label = document.createTextNode("Crop width:");
-	this.position.appendChild(crop_width_label);
+		let source_y_label = document.createTextNode("Source Y:");
+		this.position.appendChild(source_y_label);
 
-	this.crop_width = document.createElement("input");
-	this.crop_width.addEventListener("keyup", this.positionBoundary.bind(this));
-	this.position.appendChild(this.crop_width);
+		this.source_y = document.createElement("input");
+		this.source_y.type = 'number';
+		this.source_y.addEventListener("change", this.positionBoundary.bind(this));
+		this.source_y.addEventListener("keyup", this.positionBoundary.bind(this));
+		this.position.appendChild(this.source_y);
 
-	var crop_height_label = document.createTextNode("Crop height:");
-	this.position.appendChild(crop_height_label);
+		let crop_width_label = document.createTextNode("Crop width:");
+		this.position.appendChild(crop_width_label);
 
-	this.crop_height = document.createElement("input");
-	this.crop_height.addEventListener("keyup", this.positionBoundary.bind(this));
-	this.position.appendChild(this.crop_height);
+		this.crop_width = document.createElement("input");
+		this.crop_width.type = 'number';
+		this.crop_width.addEventListener("change", this.positionBoundary.bind(this));
+		this.crop_width.addEventListener("keyup", this.positionBoundary.bind(this));
+		this.position.appendChild(this.crop_width);
 
-	this.save_button = document.createElement("span");
-	this.save_button.className = "btn";
-	this.save_button.innerHTML = "Save";
-	this.save_button.addEventListener('click', this.save.bind(this));
-	this.position.appendChild(this.save_button);
+		let crop_height_label = document.createTextNode("Crop height:");
+		this.position.appendChild(crop_height_label);
 
-	this.abort_button = document.createElement("span");
-	this.abort_button.className = "btn btn-red";
-	this.abort_button.innerHTML = "Abort";
-	this.abort_button.addEventListener('click', this.hide.bind(this));
-	this.position.appendChild(this.abort_button);
+		this.crop_height = document.createElement("input");
+		this.crop_height.type = 'number';
+		this.crop_height.addEventListener("change", this.positionBoundary.bind(this));
+		this.crop_height.addEventListener("keyup", this.positionBoundary.bind(this));
+		this.position.appendChild(this.crop_height);
 
-	this.image_container = document.createElement("div");
-	this.image_container.className = "crop_image_container";
-	this.container.appendChild(this.image_container);
+		this.crop_constrain_label = document.createElement("label");
+		this.position.appendChild(this.crop_constrain_label);
 
-	this.crop_boundary = document.createElement("div");
-	this.crop_boundary.id = "crop_boundary";
-	this.image_container.appendChild(this.crop_boundary);
+		this.crop_constrain = document.createElement("input");
+		this.crop_constrain.checked = true;
+		this.crop_constrain.type = 'checkbox';
+		this.crop_constrain_label.appendChild(this.crop_constrain);
 
-	this.original_image = document.createElement("img");
-	this.original_image.id = "original_image";
-	this.original_image.src = this.opt.original_image_src;
-	this.image_container.appendChild(this.original_image);
+		this.crop_constrain_text = document.createTextNode('Constrain proportions');
+		this.crop_constrain_label.appendChild(this.crop_constrain_text);
 
-	this.parent = document.getElementById(this.opt.editor_container_parent_id);
-	this.parent.appendChild(this.container);
-};
+		this.save_button = document.createElement("span");
+		this.save_button.className = "btn";
+		this.save_button.textContent = "Save";
+		this.save_button.addEventListener('click', this.save.bind(this));
+		this.position.appendChild(this.save_button);
 
-CropEditor.prototype.setInputValues = function() {
-	var current = this.thumbnail_select.options[this.thumbnail_select.selectedIndex].dataset;
+		this.abort_button = document.createElement("span");
+		this.abort_button.className = "btn btn-red";
+		this.abort_button.textContent = "Abort";
+		this.abort_button.addEventListener('click', this.hide.bind(this));
+		this.position.appendChild(this.abort_button);
+	}
 
-	if (typeof current.crop_region === "undefined") {
-		var source_ratio = this.original_image.naturalWidth / this.original_image.naturalHeight,
-			crop_ratio = current.crop_width / current.crop_height,
-			min_dim = Math.min(this.original_image.naturalWidth, this.original_image.naturalHeight);
+	initImageContainer() {
+		this.image_container = document.createElement("div");
+		this.image_container.className = "crop_image_container";
+		this.container.appendChild(this.image_container);
+
+		this.crop_boundary = document.createElement("div");
+		this.crop_boundary.id = "crop_boundary";
+		this.image_container.appendChild(this.crop_boundary);
+
+		this.original_image = document.createElement("img");
+		this.original_image.draggable = false;
+		this.original_image.id = "original_image";
+		this.original_image.src = this.opt.original_image_src;
+		this.image_container.appendChild(this.original_image);
+	}
+
+	setDefaultCrop(cropAspectRatio, cropMethod) {
+		let source = this.original_image;
+		let sourceAspectRatio = source.naturalWidth / source.naturalHeight;
 
 		// Cropping from the centre?
-		if (current.crop_method === "c") {
+		if (cropMethod === "c" || cropMethod === "s") {
 			// Crop vertically from the centre, using the entire width.
-			if (source_ratio < crop_ratio) {
-				this.crop_width.value = this.original_image.naturalWidth;
-				this.crop_height.value = Math.ceil(this.original_image.naturalWidth / crop_ratio);
+			if (sourceAspectRatio <= cropAspectRatio) {
+				this.crop_width.value = source.naturalWidth;
+				this.crop_height.value = Math.ceil(source.naturalWidth / cropAspectRatio);
 				this.source_x.value = 0;
-				this.source_y.value = Math.ceil((this.original_image.naturalHeight - this.crop_height.value) / 2);
+				this.source_y.value = Math.ceil((source.naturalHeight - this.crop_height.value) / 2);
 			}
 			// Crop horizontally from the centre, using the entire height.
 			else {
-				this.crop_width.value = Math.ceil(current.crop_width * this.original_image.naturalHeight / current.crop_height);
-				this.crop_height.value = this.original_image.naturalHeight;
-				this.source_x.value = Math.ceil((this.original_image.naturalWidth - this.crop_width.value) / 2);
+				this.crop_width.value = Math.ceil(cropAspectRatio * source.naturalHeight);
+				this.crop_height.value = source.naturalHeight;
+				this.source_x.value = Math.ceil((source.naturalWidth - this.crop_width.value) / 2);
 				this.source_y.value = 0;
 			}
 		}
 		// Cropping a top or bottom slice?
 		else {
 			// Can we actually take a top or bottom slice from the original image?
-			if (source_ratio < crop_ratio) {
-				this.crop_width.value = this.original_image.naturalWidth;
-				this.crop_height.value = Math.floor(this.original_image.naturalHeight / crop_ratio);
+			if (sourceAspectRatio <= cropAspectRatio) {
+				this.crop_width.value = source.naturalWidth;
+				this.crop_height.value = Math.floor(source.naturalWidth / cropAspectRatio);
 				this.source_x.value = "0";
-				this.source_y.value = current.crop_method.indexOf("t") !== -1 ? "0" : this.original_image.naturalHeight - this.crop_height.value;
+				this.source_y.value = cropMethod.indexOf("t") !== -1 ? "0" : source.naturalHeight - this.crop_height.value;
 			}
 			// Otherwise, take a vertical slice from the centre.
 			else {
-				this.crop_width.value = Math.floor(this.original_image.naturalHeight * crop_ratio);
-				this.crop_height.value = this.original_image.naturalHeight;
-				this.source_x.value = Math.floor((this.original_image.naturalWidth - this.crop_width.value) / 2);
+				this.crop_width.value = Math.floor(source.naturalHeight * cropAspectRatio);
+				this.crop_height.value = source.naturalHeight;
+				this.source_x.value = Math.floor((source.naturalWidth - this.crop_width.value) / 2);
 				this.source_y.value = "0";
 			}
 		}
-	} else {
-		var region = current.crop_region.split(',');
-		this.crop_width.value = region[0];
-		this.crop_height.value = region[1];
-		this.source_x.value = region[2];
-		this.source_y.value = region[3];
-	}
-};
-
-CropEditor.prototype.showContainer = function() {
-	this.container.style.display = "block";
-	this.setInputValues();
-	this.positionBoundary();
-}
-
-CropEditor.prototype.save = function() {
-	var current = this.thumbnail_select.options[this.thumbnail_select.selectedIndex].dataset;
-	var payload = {
-		thumb_width: current.crop_width,
-		thumb_height: current.crop_height,
-		crop_method: current.crop_method,
-		crop_width: this.crop_width.value,
-		crop_height: this.crop_height.value,
-		source_x: this.source_x.value,
-		source_y: this.source_y.value
-	};
-	var req = HttpRequest("post", this.opt.submitUrl + "?id=" + this.opt.asset_id + "&updatethumb",
-		"data=" + encodeURIComponent(JSON.stringify(payload)), function(response) {
-			this.opt.after_save(response);
-			this.hide();
-		}.bind(this));
-};
-
-CropEditor.prototype.show = function() {
-	if (typeof this.container === "undefined") {
-		this.buildContainer();
 	}
 
-	// Defer showing and positioning until image is loaded.
-	// !!! TODO: add a spinner in the mean time?
-	if (this.original_image.naturalWidth > 0) {
-		this.showContainer();
-	} else {
-		this.original_image.addEventListener("load", function() {
+	setPositionFormValues() {
+		let current = this.thumbnail_select.options[this.thumbnail_select.selectedIndex].dataset;
+
+		if (typeof current.crop_region === "undefined") {
+			let aspectRatio = current.crop_width / current.crop_height;
+			this.setDefaultCrop(aspectRatio, current.crop_method);
+		} else {
+			let region = current.crop_region.split(',');
+			this.crop_width.value = region[0];
+			this.crop_height.value = region[1];
+			this.source_x.value = region[2];
+			this.source_y.value = region[3];
+		}
+
+		this.crop_width.min = 1;
+		this.crop_height.min = 1;
+		this.source_x.min = 0;
+		this.source_y.min = 0;
+
+		let source = this.original_image;
+		this.crop_width.max = source.naturalWidth;
+		this.crop_height.max = source.naturalHeight;
+		this.source_x.max = source.naturalWidth - 1;
+		this.source_y.max = source.naturalHeight - 1;
+
+		this.crop_constrain_text.textContent = `Constrain proportions (${current.crop_width} × ${current.crop_height})`;
+	}
+
+	showContainer() {
+		this.container.style.display = '';
+		this.setPositionFormValues();
+		this.positionBoundary();
+		this.addEvents();
+	}
+
+	save() {
+		let current = this.thumbnail_select.options[this.thumbnail_select.selectedIndex].dataset;
+		let payload = {
+			thumb_width: current.crop_width,
+			thumb_height: current.crop_height,
+			crop_method: current.crop_method,
+			crop_width: this.crop_width.value,
+			crop_height: this.crop_height.value,
+			source_x: this.source_x.value,
+			source_y: this.source_y.value
+		};
+		let req = HttpRequest("post", this.opt.submitUrl + "?id=" + this.opt.asset_id + "&updatethumb",
+			"data=" + encodeURIComponent(JSON.stringify(payload)), function(response) {
+				this.opt.after_save(response);
+				this.hide();
+			}.bind(this));
+	}
+
+	show() {
+		if (typeof this.container === "undefined") {
+			this.initDOM();
+		}
+
+		// Defer showing and positioning until image is loaded.
+		// !!! TODO: add a spinner in the mean time?
+		if (this.original_image.naturalWidth > 0) {
 			this.showContainer();
-		}.bind(this));
+		} else {
+			this.original_image.addEventListener("load", event => this.showContainer());
+		}
 	}
-};
 
-CropEditor.prototype.hide = function() {
-	this.container.style.display = "none";
-};
+	hide() {
+		this.container.style.display = "none";
+	}
 
-CropEditor.prototype.addEvents = function(event) {
-	var drag_target = document.getElementById(opt.drag_target);
-	drag_target.addEventListener('dragstart', this.dragStart);
-	drag_target.addEventListener('drag', this.drag);
-	drag_target.addEventListener('dragend', this.dragEnd);
-};
+	addEvents(event) {
+		let cropTarget = this.image_container;
+		cropTarget.addEventListener('mousedown', this.cropSelectionStart.bind(this));
+		cropTarget.addEventListener('mousemove', this.cropSelection.bind(this));
+		cropTarget.addEventListener('mouseup', this.cropSelectionEnd.bind(this));
+		// cropTarget.addEventListener('mouseout', this.cropSelectionEnd.bind(this));
 
-CropEditor.prototype.dragStart = function(event) {
-	console.log(event);
-	event.preventDefault();
-};
+		this.original_image.addEventListener('mousedown', event => {return false});
+		this.original_image.addEventListener('dragstart', event => {return false});
 
-CropEditor.prototype.dragEnd = function(event) {
-	console.log(event);
-};
+		let moveTarget = this.crop_boundary;
+		moveTarget.addEventListener('mousedown', this.moveSelectionStart.bind(this));
+		moveTarget.addEventListener('mousemove', this.moveSelection.bind(this));
+		moveTarget.addEventListener('mouseup', this.moveSelectionEnd.bind(this));
 
-CropEditor.prototype.drag = function(event) {
-	console.log(event);
-};
+		window.addEventListener('resize', this.positionBoundary.bind(this));
+	}
 
-CropEditor.prototype.toggleCropButton = function() {
-	var current = this.thumbnail_select.options[this.thumbnail_select.selectedIndex].dataset;
-	this.edit_crop_button.style.display = typeof current.crop_method === "undefined" ? "none" : "";
-};
+	cropSelectionStart(event) {
+		if (this.isMoving) {
+			return false;
+		}
 
-CropEditor.prototype.positionBoundary = function(event) {
-	var source_x = parseInt(this.source_x.value),
-		source_y = parseInt(this.source_y.value),
-		crop_width = parseInt(this.crop_width.value),
-		crop_height = parseInt(this.crop_height.value),
-		real_width = this.original_image.naturalWidth,
-		real_height = this.original_image.naturalHeight,
-		scaled_width = this.original_image.clientWidth,
-		scaled_height = this.original_image.clientHeight;
+		let dragStartX = event.x - this.image_container.offsetLeft;
+		let dragStartY = event.y - this.image_container.offsetTop;
 
-	var width_scale = scaled_width / real_width,
-		height_scale = scaled_height / real_height;
+		if (dragStartX > this.original_image.clientWidth ||
+			dragStartY > this.original_image.clientHeight) {
+			return;
+		}
 
-	crop_boundary.style.left = (this.source_x.value) * width_scale + "px";
-	crop_boundary.style.top = (this.source_y.value) * height_scale + "px";
-	crop_boundary.style.width = (this.crop_width.value) * width_scale + "px";
-	crop_boundary.style.height = (this.crop_height.value) * height_scale + "px";
-};
+		this.isDragging = true;
+		this.dragStartX = dragStartX;
+		this.dragStartY = dragStartY;
+	}
+
+	cropSelectionEnd(event) {
+		this.isDragging = false;
+		this.handleCropSelectionEvent(event);
+	}
+
+	cropSelection(event) {
+		this.handleCropSelectionEvent(event);
+	}
+
+	getScaleFactor() {
+		return this.original_image.naturalWidth / this.original_image.clientWidth;
+	}
+
+	handleCropSelectionEvent(event) {
+		if (!this.isDragging) {
+			return;
+		}
+
+		this.dragEndX = event.x - this.image_container.offsetLeft;
+		this.dragEndY = event.y - this.image_container.offsetTop;
+
+		let scaleFactor = this.getScaleFactor();
+
+		this.source_x.value = Math.ceil(Math.min(this.dragStartX, this.dragEndX) * scaleFactor);
+		this.source_y.value = Math.ceil(Math.min(this.dragStartY, this.dragEndY) * scaleFactor);
+
+		let width = Math.ceil(Math.abs(this.dragEndX - this.dragStartX) * scaleFactor);
+		this.crop_width.value = Math.min(width, this.original_image.naturalWidth - this.source_x.value);
+
+		let height = Math.ceil(Math.abs(this.dragEndY - this.dragStartY) * scaleFactor);
+		this.crop_height.value = Math.min(height, this.original_image.naturalHeight - this.source_y.value);
+
+		if (this.crop_constrain.checked) {
+			let current = this.thumbnail_select.options[this.thumbnail_select.selectedIndex].dataset;
+
+			let currentAspectRatio = parseInt(this.crop_width.value) / parseInt(this.crop_height.value);
+			let targetAspectRatio = current.crop_width / current.crop_height;
+
+			if (Math.abs(currentAspectRatio - targetAspectRatio) > 0.001) {
+				// Landscape?
+				if (targetAspectRatio > 1.0) {
+					let height = Math.ceil(this.crop_width.value / targetAspectRatio);
+					if (parseInt(this.source_y.value) + height > this.original_image.naturalHeight) {
+						height = this.original_image.naturalHeight - this.source_y.value;
+					}
+					this.crop_width.value = height * targetAspectRatio;
+					this.crop_height.value = height;
+				}
+				// Portrait?
+				else {
+					let width = Math.ceil(this.crop_height.value * targetAspectRatio);
+					if (parseInt(this.source_x.value) + width > this.original_image.naturalWidth) {
+						width = this.original_image.naturalWidth - this.source_x.value;
+					}
+					this.crop_width.value = width;
+					this.crop_height.value = width / targetAspectRatio;
+				}
+			}
+		}
+
+		this.positionBoundary();
+	}
+
+	handleCropMoveEvent(event) {
+		if (!this.isMoving) {
+			return;
+		}
+
+		this.dragEndX = event.x - this.crop_boundary.offsetLeft;
+		this.dragEndY = event.y - this.crop_boundary.offsetTop;
+
+		let scaleFactor = this.getScaleFactor();
+
+		let x = parseInt(this.source_x.value) + Math.ceil((this.dragEndX - this.dragStartX) * scaleFactor);
+		if (x + parseInt(this.crop_width.value) > this.original_image.naturalWidth) {
+			x += this.original_image.naturalWidth - (x + parseInt(this.crop_width.value));
+		}
+		this.source_x.value = Math.max(x, 0);
+
+		let y = parseInt(this.source_y.value) + Math.ceil((this.dragEndY - this.dragStartY) * scaleFactor);
+		if (y + parseInt(this.crop_height.value) > this.original_image.naturalHeight) {
+			y += this.original_image.naturalHeight - (y + parseInt(this.crop_height.value));
+		}
+		this.source_y.value = Math.max(y, 0);
+
+		this.positionBoundary();
+	}
+
+	moveSelectionStart(event) {
+		if (this.isDragging) {
+			return false;
+		}
+		this.isMoving = true;
+		this.dragStartX = event.x - this.crop_boundary.offsetLeft;
+		this.dragStartY = event.y - this.crop_boundary.offsetTop;
+	}
+
+	moveSelectionEnd(event) {
+		this.isMoving = false;
+		this.handleCropMoveEvent(event);
+	}
+
+	moveSelection(event) {
+		this.handleCropMoveEvent(event);
+	}
+
+	toggleCropButton() {
+		let current = this.thumbnail_select.options[this.thumbnail_select.selectedIndex].dataset;
+		this.edit_crop_button.style.display = typeof current.crop_method === "undefined" ? "none" : "";
+	}
+
+	positionBoundary(event) {
+		let scaleFactor = this.getScaleFactor();
+		crop_boundary.style.left = parseInt(this.source_x.value) / scaleFactor + "px";
+		crop_boundary.style.top = parseInt(this.source_y.value) / scaleFactor + "px";
+		crop_boundary.style.width = parseInt(this.crop_width.value) / scaleFactor + "px";
+		crop_boundary.style.height = parseInt(this.crop_height.value) / scaleFactor + "px";
+	}
+}
diff --git a/templates/EditAssetForm.php b/templates/EditAssetForm.php
index 1dd3ed6..490b0d2 100644
--- a/templates/EditAssetForm.php
+++ b/templates/EditAssetForm.php
@@ -138,10 +138,10 @@ class EditAssetForm extends SubTemplate
 					<h3>Thumbnails</h3>
 					View: <select id="thumbnail_src">';
 
-		foreach ($this->thumbs as $thumb)
+		$first = INF;
+		foreach ($this->thumbs as $i => $thumb)
 		{
-			if (!$thumb['status'])
-				continue;
+			$first = min($i, $first);
 
 			echo '
 						<option data-url="', $thumb['url'], '" data-crop_width="', $thumb['dimensions'][0], '" data-crop_height="', $thumb['dimensions'][1], '"',
@@ -171,18 +171,16 @@ class EditAssetForm extends SubTemplate
 
 		echo '
 					</select>
-					<a id="thumbnail_link" href="', $this->thumbs[0]['url'], '" target="_blank">
-						<img id="thumbnail" src="', $this->thumbs[0]['url'], '" alt="Thumbnail" style="width: 100%; height: auto;">
+					<a id="thumbnail_link" href="', $this->thumbs[$first]['url'], '" target="_blank">
+						<img id="thumbnail" src="', $this->thumbs[$first]['url'], '" alt="Thumbnail" style="width: 100%; height: auto;">
 					</a>
 				</div>
-				<script type="text/javascript">
-					setTimeout(function() {
-						document.getElementById("thumbnail_src").addEventListener("change", function(event) {
-							var selection = event.target.options[event.target.selectedIndex];
-							document.getElementById("thumbnail_link").href = selection.dataset.url;
-							document.getElementById("thumbnail").src = selection.dataset.url;
-						});
-					}, 100);
+				<script type="text/javascript" defer="defer">
+					document.getElementById("thumbnail_src").addEventListener("change", event => {
+						let selection = event.target.options[event.target.selectedIndex];
+						document.getElementById("thumbnail_link").href = selection.dataset.url;
+						document.getElementById("thumbnail").src = selection.dataset.url;
+					});
 				</script>';
 	}
 
@@ -193,27 +191,27 @@ class EditAssetForm extends SubTemplate
 
 		echo '
 				<script type="text/javascript" src="', BASEURL, '/js/crop_editor.js"></script>
-				<script type="text/javascript">
-					setTimeout(function() {
-						var editor = new CropEditor({
-							submit_url: "', BASEURL, '/editasset/",
-							original_image_src: "', $this->asset->getUrl(), '",
-							editor_container_parent_id: "asset_form",
-							thumbnail_select_id: "thumbnail_src",
-							drag_target: "drag_target",
-							asset_id: ', $this->asset->getId(), ',
-							after_save: function(data) {
-								// Update thumbnail
-								document.getElementById("thumbnail").src = data.url + "?" + (new Date()).getTime();
+				<script type="text/javascript" defer="defer">
+					let editor = new CropEditor({
+						submit_url: "', BASEURL, '/editasset/",
+						original_image_src: "', $this->asset->getUrl(), '",
+						editor_container_parent_id: "asset_form",
+						thumbnail_select_id: "thumbnail_src",
+						drag_target: ".crop_image_container",
+						asset_id: ', $this->asset->getId(), ',
+						after_save: function(data) {
+							// Update thumbnail
+							document.getElementById("thumbnail").src = data.url + "?" + (new Date()).getTime();
 
-								// Update select
-								var src = document.getElementById("thumbnail_src");
-								src.options[src.selectedIndex].dataset.crop_region = data.value;
+							// Update select
+							let src = document.getElementById("thumbnail_src");
+							let option = src.options[src.selectedIndex];
+							option.dataset.crop_region = data.value;
+							option.textContent = option.textContent.replace(/top|bottom|centre|slice/, "exact");
 
-								// TODO: update meta
-							}
-						});
-					}, 100);
+							// TODO: update meta
+						}
+					});
 				</script>';
 	}
 
@@ -256,9 +254,6 @@ class EditAssetForm extends SubTemplate
 
 		foreach ($this->thumbs as $thumb)
 		{
-			if (!$thumb['status'])
-				continue;
-
 			echo '
 						<option value="thumb_', implode('x', $thumb['dimensions']);