diff --git a/ext/bg/js/settings/popup-menu.js b/ext/bg/js/settings/popup-menu.js
new file mode 100644
index 00000000..02ab67d2
--- /dev/null
+++ b/ext/bg/js/settings/popup-menu.js
@@ -0,0 +1,159 @@
+/*
+ * Copyright (C) 2020  Yomichan Authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+class PopupMenu {
+    constructor(sourceElement, container) {
+        this._sourceElement = sourceElement;
+        this._container = container;
+        this._isClosed = false;
+        this._eventListeners = new EventListenerCollection();
+    }
+
+    prepare() {
+        const menu = this._container.querySelector('.popup-menu');
+        const items = menu.querySelectorAll('.popup-menu-item');
+        this._setPosition(menu, items);
+        menu.focus();
+
+        this._eventListeners.addEventListener(window, 'resize', this._onWindowResize.bind(this), false);
+        this._eventListeners.addEventListener(this._container, 'click', this._onMenuContainerClick.bind(this), false);
+
+        const onMenuItemClick = this._onMenuItemClick.bind(this);
+        for (const item of items) {
+            this._eventListeners.addEventListener(item, 'click', onMenuItemClick, false);
+        }
+    }
+
+    close() {
+        this._close(null);
+    }
+
+    // Private
+
+    _onMenuContainerClick(e) {
+        if (e.currentTarget !== e.target) { return; }
+        this._close(null, 'close');
+    }
+
+    _onMenuItemClick(e) {
+        const item = e.currentTarget;
+        if (item.disabled) { return; }
+        this._close(item, 'item');
+    }
+
+    _onWindowResize() {
+        this._close(null, 'resize');
+    }
+
+    _setPosition(menu, items) {
+        // Get flags
+        let horizontal = 1;
+        let vertical = 1;
+        let horizontalCover = 1;
+        let verticalCover = 1;
+        const positionInfo = this._sourceElement.dataset.menuPosition;
+        if (typeof positionInfo === 'string') {
+            const positionInfoSet = new Set(positionInfo.split(','));
+
+            if (positionInfoSet.has('left')) {
+                horizontal = -1;
+            } else if (positionInfoSet.has('right')) {
+                horizontal = 1;
+            } else if (positionInfoSet.has('h-center')) {
+                horizontal = 0;
+            }
+
+            if (positionInfoSet.has('above')) {
+                vertical = -1;
+            } else if (positionInfoSet.has('below')) {
+                vertical = 1;
+            } else if (positionInfoSet.has('v-center')) {
+                vertical = 0;
+            }
+
+            if (positionInfoSet.has('cover')) {
+                horizontalCover = 1;
+                verticalCover = 1;
+            } else if (positionInfoSet.has('no-cover')) {
+                horizontalCover = -1;
+                verticalCover = -1;
+            }
+
+            if (positionInfoSet.has('h-cover')) {
+                horizontalCover = 1;
+            } else if (positionInfoSet.has('no-h-cover')) {
+                horizontalCover = -1;
+            }
+
+            if (positionInfoSet.has('v-cover')) {
+                verticalCover = 1;
+            } else if (positionInfoSet.has('no-v-cover')) {
+                verticalCover = -1;
+            }
+        }
+
+        // Position
+        const fullRect = this._container.getBoundingClientRect();
+        const sourceRect = this._sourceElement.getBoundingClientRect();
+        const menuRect = menu.getBoundingClientRect();
+        let top = menuRect.top;
+        let bottom = menuRect.bottom;
+        if (verticalCover === 1 && items.length > 0) {
+            const rect1 = items[0].getBoundingClientRect();
+            const rect2 = items[items.length - 1].getBoundingClientRect();
+            top = rect1.top;
+            bottom = rect2.bottom;
+        }
+
+        let x = (
+            sourceRect.left +
+            sourceRect.width * ((-horizontal * horizontalCover + 1) * 0.5) +
+            menuRect.width * ((-horizontal + 1) * -0.5)
+        );
+        let y = (
+            sourceRect.top +
+            (menuRect.top - top) +
+            sourceRect.height * ((-vertical * verticalCover + 1) * 0.5) +
+            (bottom - top) * ((-vertical + 1) * -0.5)
+        );
+
+        x = Math.max(0.0, Math.min(fullRect.width - menuRect.width, x));
+        y = Math.max(0.0, Math.min(fullRect.height - menuRect.height, y));
+
+        menu.style.left = `${x}px`;
+        menu.style.top = `${y}px`;
+    }
+
+    _close(item, cause) {
+        if (this._isClosed) { return; }
+        const action = (item !== null ? item.dataset.menuAction : null);
+
+        this._sourceElement.dispatchEvent(new CustomEvent('menuClosed', {
+            bubbles: false,
+            detail: {
+                item,
+                action,
+                cause
+            }
+        }));
+
+        this._eventListeners.removeAllEventListeners();
+        if (this._container.parentNode !== null) {
+            this._container.parentNode.removeChild(this._container);
+        }
+    }
+}