diff --git a/framework/core/js/src/admin/AdminApplication.ts b/framework/core/js/src/admin/AdminApplication.ts
index 69079b5df..3634b2b58 100644
--- a/framework/core/js/src/admin/AdminApplication.ts
+++ b/framework/core/js/src/admin/AdminApplication.ts
@@ -40,6 +40,7 @@ export interface AdminApplicationData extends ApplicationData {
   modelStatistics: Record<string, { total: number }>;
   displayNameDrivers: string[];
   slugDrivers: Record<string, string[]>;
+  permissions: Record<string, string[]>;
 }
 
 export default class AdminApplication extends Application {
diff --git a/framework/core/js/src/admin/components/PermissionDropdown.js b/framework/core/js/src/admin/components/PermissionDropdown.tsx
similarity index 65%
rename from framework/core/js/src/admin/components/PermissionDropdown.js
rename to framework/core/js/src/admin/components/PermissionDropdown.tsx
index aa635d925..42c0fd718 100644
--- a/framework/core/js/src/admin/components/PermissionDropdown.js
+++ b/framework/core/js/src/admin/components/PermissionDropdown.tsx
@@ -1,18 +1,19 @@
 import app from '../../admin/app';
-import Dropdown from '../../common/components/Dropdown';
+import Dropdown, { IDropdownAttrs } from '../../common/components/Dropdown';
 import Button from '../../common/components/Button';
 import Separator from '../../common/components/Separator';
 import Group from '../../common/models/Group';
 import Badge from '../../common/components/Badge';
 import GroupBadge from '../../common/components/GroupBadge';
+import Mithril from 'mithril';
 
-function badgeForId(id) {
+function badgeForId(id: string) {
   const group = app.store.getById('groups', id);
 
   return group ? GroupBadge.component({ group, label: null }) : '';
 }
 
-function filterByRequiredPermissions(groupIds, permission) {
+function filterByRequiredPermissions(groupIds: string[], permission: string) {
   app.getRequiredPermissions(permission).forEach((required) => {
     const restrictToGroupIds = app.data.permissions[required] || [];
 
@@ -32,24 +33,28 @@ function filterByRequiredPermissions(groupIds, permission) {
   return groupIds;
 }
 
-export default class PermissionDropdown extends Dropdown {
-  static initAttrs(attrs) {
+export interface IPermissionDropdownAttrs extends IDropdownAttrs {
+  permission: string;
+}
+
+export default class PermissionDropdown<CustomAttrs extends IPermissionDropdownAttrs = IPermissionDropdownAttrs> extends Dropdown<CustomAttrs> {
+  static initAttrs(attrs: IPermissionDropdownAttrs) {
     super.initAttrs(attrs);
 
     attrs.className = 'PermissionDropdown';
     attrs.buttonClassName = 'Button Button--text';
   }
 
-  view(vnode) {
+  view(vnode: Mithril.Vnode<CustomAttrs, this>) {
     const children = [];
 
     let groupIds = app.data.permissions[this.attrs.permission] || [];
 
     groupIds = filterByRequiredPermissions(groupIds, this.attrs.permission);
 
-    const everyone = groupIds.indexOf(Group.GUEST_ID) !== -1;
-    const members = groupIds.indexOf(Group.MEMBER_ID) !== -1;
-    const adminGroup = app.store.getById('groups', Group.ADMINISTRATOR_ID);
+    const everyone = groupIds.includes(Group.GUEST_ID);
+    const members = groupIds.includes(Group.MEMBER_ID);
+    const adminGroup = app.store.getById<Group>('groups', Group.ADMINISTRATOR_ID)!;
 
     if (everyone) {
       this.attrs.label = Badge.component({ icon: 'fas fa-globe' });
@@ -89,40 +94,42 @@ export default class PermissionDropdown extends Dropdown {
           {
             icon: !everyone && !members ? 'fas fa-check' : true,
             disabled: !everyone && !members,
-            onclick: (e) => {
+            onclick: (e: MouseEvent) => {
               if (e.shiftKey) e.stopPropagation();
               this.save([]);
             },
           },
-          [badgeForId(adminGroup.id()), ' ', adminGroup.namePlural()]
+          [badgeForId(adminGroup.id()!), ' ', adminGroup.namePlural()]
         )
       );
 
-      [].push.apply(
-        children,
-        app.store
-          .all('groups')
-          .filter((group) => [Group.ADMINISTRATOR_ID, Group.GUEST_ID, Group.MEMBER_ID].indexOf(group.id()) === -1)
-          .map((group) =>
-            Button.component(
-              {
-                icon: groupIds.indexOf(group.id()) !== -1 ? 'fas fa-check' : true,
-                onclick: (e) => {
-                  if (e.shiftKey) e.stopPropagation();
-                  this.toggle(group.id());
-                },
-                disabled: this.isGroupDisabled(group.id()) && this.isGroupDisabled(Group.MEMBER_ID) && this.isGroupDisabled(Group.GUEST_ID),
+      // These groups are defined above, appearing first in the list.
+      const excludedGroups = [Group.ADMINISTRATOR_ID, Group.GUEST_ID, Group.MEMBER_ID];
+
+      const groupButtons = app.store
+        .all<Group>('groups')
+        .filter((group) => !excludedGroups.includes(group.id()!))
+        .map((group) =>
+          Button.component(
+            {
+              icon: groupIds.includes(group.id()!) ? 'fas fa-check' : true,
+              onclick: (e: MouseEvent) => {
+                if (e.shiftKey) e.stopPropagation();
+                this.toggle(group.id()!);
               },
-              [badgeForId(group.id()), ' ', group.namePlural()]
-            )
+              disabled: this.isGroupDisabled(group.id()!) && this.isGroupDisabled(Group.MEMBER_ID) && this.isGroupDisabled(Group.GUEST_ID),
+            },
+            [badgeForId(group.id()!), ' ', group.namePlural()]
           )
-      );
+        );
+
+      children.push(...groupButtons);
     }
 
     return super.view({ ...vnode, children });
   }
 
-  save(groupIds) {
+  save(groupIds: string[]) {
     const permission = this.attrs.permission;
 
     app.data.permissions[permission] = groupIds;
@@ -134,7 +141,7 @@ export default class PermissionDropdown extends Dropdown {
     });
   }
 
-  toggle(groupId) {
+  toggle(groupId: string) {
     const permission = this.attrs.permission;
 
     let groupIds = app.data.permissions[permission] || [];
@@ -151,7 +158,7 @@ export default class PermissionDropdown extends Dropdown {
     this.save(groupIds);
   }
 
-  isGroupDisabled(id) {
-    return filterByRequiredPermissions([id], this.attrs.permission).indexOf(id) === -1;
+  isGroupDisabled(id: string) {
+    return !filterByRequiredPermissions([id], this.attrs.permission).includes(id);
   }
 }
diff --git a/framework/core/js/src/admin/components/SessionDropdown.js b/framework/core/js/src/admin/components/SessionDropdown.tsx
similarity index 69%
rename from framework/core/js/src/admin/components/SessionDropdown.js
rename to framework/core/js/src/admin/components/SessionDropdown.tsx
index 9e28775b4..e7606793a 100644
--- a/framework/core/js/src/admin/components/SessionDropdown.js
+++ b/framework/core/js/src/admin/components/SessionDropdown.tsx
@@ -1,16 +1,19 @@
 import app from '../../admin/app';
 import avatar from '../../common/helpers/avatar';
 import username from '../../common/helpers/username';
-import Dropdown from '../../common/components/Dropdown';
+import Dropdown, { IDropdownAttrs } from '../../common/components/Dropdown';
 import Button from '../../common/components/Button';
 import ItemList from '../../common/utils/ItemList';
+import type Mithril from 'mithril';
+
+export interface ISessionDropdownAttrs extends IDropdownAttrs {}
 
 /**
  * The `SessionDropdown` component shows a button with the current user's
  * avatar/name, with a dropdown of session controls.
  */
-export default class SessionDropdown extends Dropdown {
-  static initAttrs(attrs) {
+export default class SessionDropdown<CustomAttrs extends ISessionDropdownAttrs = ISessionDropdownAttrs> extends Dropdown<CustomAttrs> {
+  static initAttrs(attrs: ISessionDropdownAttrs) {
     super.initAttrs(attrs);
 
     attrs.className = 'SessionDropdown';
@@ -18,7 +21,7 @@ export default class SessionDropdown extends Dropdown {
     attrs.menuClassName = 'Dropdown-menu--right';
   }
 
-  view(vnode) {
+  view(vnode: Mithril.Vnode<CustomAttrs, this>) {
     return super.view({ ...vnode, children: this.items().toArray() });
   }
 
@@ -30,11 +33,9 @@ export default class SessionDropdown extends Dropdown {
 
   /**
    * Build an item list for the contents of the dropdown menu.
-   *
-   * @return {ItemList}
    */
-  items() {
-    const items = new ItemList();
+  items(): ItemList<Mithril.Children> {
+    const items = new ItemList<Mithril.Children>();
 
     items.add(
       'logOut',
diff --git a/framework/core/js/src/admin/components/SettingDropdown.js b/framework/core/js/src/admin/components/SettingDropdown.tsx
similarity index 50%
rename from framework/core/js/src/admin/components/SettingDropdown.js
rename to framework/core/js/src/admin/components/SettingDropdown.tsx
index 91953d67e..975fd2246 100644
--- a/framework/core/js/src/admin/components/SettingDropdown.js
+++ b/framework/core/js/src/admin/components/SettingDropdown.tsx
@@ -1,10 +1,21 @@
 import app from '../app';
-import SelectDropdown from '../../common/components/SelectDropdown';
+import SelectDropdown, { ISelectDropdownAttrs } from '../../common/components/SelectDropdown';
 import Button from '../../common/components/Button';
 import saveSettings from '../utils/saveSettings';
+import Mithril from 'mithril';
 
-export default class SettingDropdown extends SelectDropdown {
-  static initAttrs(attrs) {
+export type SettingDropdownOption = {
+  value: any;
+  label: string;
+};
+
+export interface ISettingDropdownAttrs extends ISelectDropdownAttrs {
+  setting?: string;
+  options: Array<SettingDropdownOption>;
+}
+
+export default class SettingDropdown<CustomAttrs extends ISettingDropdownAttrs = ISettingDropdownAttrs> extends SelectDropdown<CustomAttrs> {
+  static initAttrs(attrs: ISettingDropdownAttrs) {
     super.initAttrs(attrs);
 
     attrs.className = 'SettingDropdown';
@@ -13,21 +24,21 @@ export default class SettingDropdown extends SelectDropdown {
     attrs.defaultLabel = 'Custom';
 
     if ('key' in attrs) {
-      attrs.setting = attrs.key;
+      attrs.setting = attrs.key?.toString();
       delete attrs.key;
     }
   }
 
-  view(vnode) {
+  view(vnode: Mithril.Vnode<CustomAttrs, this>) {
     return super.view({
       ...vnode,
       children: this.attrs.options.map(({ value, label }) => {
-        const active = app.data.settings[this.attrs.setting] === value;
+        const active = app.data.settings[this.attrs.setting!] === value;
 
         return Button.component(
           {
             icon: active ? 'fas fa-check' : true,
-            onclick: saveSettings.bind(this, { [this.attrs.setting]: value }),
+            onclick: saveSettings.bind(this, { [this.attrs.setting!]: value }),
             active,
           },
           label
diff --git a/framework/core/js/src/common/components/Dropdown.js b/framework/core/js/src/common/components/Dropdown.js
deleted file mode 100644
index 47c63b3a3..000000000
--- a/framework/core/js/src/common/components/Dropdown.js
+++ /dev/null
@@ -1,140 +0,0 @@
-import app from '../../common/app';
-import Component from '../Component';
-import icon from '../helpers/icon';
-import listItems from '../helpers/listItems';
-
-/**
- * The `Dropdown` component displays a button which, when clicked, shows a
- * dropdown menu beneath it.
- *
- * ### Attrs
- *
- * - `buttonClassName` A class name to apply to the dropdown toggle button.
- * - `menuClassName` A class name to apply to the dropdown menu.
- * - `icon` The name of an icon to show in the dropdown toggle button.
- * - `caretIcon` The name of an icon to show on the right of the button.
- * - `label` The label of the dropdown toggle button. Defaults to 'Controls'.
- * - `accessibleToggleLabel` The label used to describe the dropdown toggle button to assistive readers. Defaults to 'Toggle dropdown menu'.
- * - `onhide`
- * - `onshow`
- *
- * The children will be displayed as a list inside of the dropdown menu.
- */
-export default class Dropdown extends Component {
-  static initAttrs(attrs) {
-    attrs.className = attrs.className || '';
-    attrs.buttonClassName = attrs.buttonClassName || '';
-    attrs.menuClassName = attrs.menuClassName || '';
-    attrs.label = attrs.label || '';
-    attrs.caretIcon = typeof attrs.caretIcon !== 'undefined' ? attrs.caretIcon : 'fas fa-caret-down';
-    attrs.accessibleToggleLabel = attrs.accessibleToggleLabel || app.translator.trans('core.lib.dropdown.toggle_dropdown_accessible_label');
-  }
-
-  oninit(vnode) {
-    super.oninit(vnode);
-
-    this.showing = false;
-  }
-
-  view(vnode) {
-    const items = vnode.children ? listItems(vnode.children) : [];
-    const renderItems = this.attrs.lazyDraw ? this.showing : true;
-
-    return (
-      <div className={'ButtonGroup Dropdown dropdown ' + this.attrs.className + ' itemCount' + items.length + (this.showing ? ' open' : '')}>
-        {this.getButton(vnode.children)}
-        {renderItems && this.getMenu(items)}
-      </div>
-    );
-  }
-
-  oncreate(vnode) {
-    super.oncreate(vnode);
-
-    // When opening the dropdown menu, work out if the menu goes beyond the
-    // bottom of the viewport. If it does, we will apply class to make it show
-    // above the toggle button instead of below it.
-    this.$().on('shown.bs.dropdown', () => {
-      const { lazyDraw, onshow } = this.attrs;
-
-      this.showing = true;
-
-      // If using lazy drawing, redraw before calling `onshow` function
-      // to make sure the menu DOM exists in case the callback tries to use it.
-      if (lazyDraw) {
-        m.redraw.sync();
-      }
-
-      if (typeof onshow === 'function') {
-        onshow();
-      }
-
-      // If not using lazy drawing, keep previous functionality
-      // of redrawing after calling onshow()
-      if (!lazyDraw) {
-        m.redraw();
-      }
-
-      const $menu = this.$('.Dropdown-menu');
-      const isRight = $menu.hasClass('Dropdown-menu--right');
-
-      $menu.removeClass('Dropdown-menu--top Dropdown-menu--right');
-
-      $menu.toggleClass('Dropdown-menu--top', $menu.offset().top + $menu.height() > $(window).scrollTop() + $(window).height());
-
-      if ($menu.offset().top < 0) {
-        $menu.removeClass('Dropdown-menu--top');
-      }
-
-      $menu.toggleClass('Dropdown-menu--right', isRight || $menu.offset().left + $menu.width() > $(window).scrollLeft() + $(window).width());
-    });
-
-    this.$().on('hidden.bs.dropdown', () => {
-      this.showing = false;
-
-      if (this.attrs.onhide) {
-        this.attrs.onhide();
-      }
-
-      m.redraw();
-    });
-  }
-
-  /**
-   * Get the template for the button.
-   *
-   * @return {import('mithril').Children}
-   * @protected
-   */
-  getButton(children) {
-    return (
-      <button
-        className={'Dropdown-toggle ' + this.attrs.buttonClassName}
-        aria-haspopup="menu"
-        aria-label={this.attrs.accessibleToggleLabel}
-        data-toggle="dropdown"
-        onclick={this.attrs.onclick}
-      >
-        {this.getButtonContent(children)}
-      </button>
-    );
-  }
-
-  /**
-   * Get the template for the button's content.
-   *
-   * @return {import('mithril').Children}
-   * @protected
-   */
-  getButtonContent(children) {
-    return [
-      this.attrs.icon ? icon(this.attrs.icon, { className: 'Button-icon' }) : '',
-      <span className="Button-label">{this.attrs.label}</span>,
-      this.attrs.caretIcon ? icon(this.attrs.caretIcon, { className: 'Button-caret' }) : '',
-    ];
-  }
-
-  getMenu(items) {
-    return <ul className={'Dropdown-menu dropdown-menu ' + this.attrs.menuClassName}>{items}</ul>;
-  }
-}
diff --git a/framework/core/js/src/common/components/Dropdown.tsx b/framework/core/js/src/common/components/Dropdown.tsx
new file mode 100644
index 000000000..9592fb256
--- /dev/null
+++ b/framework/core/js/src/common/components/Dropdown.tsx
@@ -0,0 +1,152 @@
+import app from '../../common/app';
+import Component, { ComponentAttrs } from '../Component';
+import icon from '../helpers/icon';
+import listItems, { ModdedChildrenWithItemName } from '../helpers/listItems';
+import extractText from '../utils/extractText';
+import type Mithril from 'mithril';
+
+export interface IDropdownAttrs extends ComponentAttrs {
+  /** A class name to apply to the dropdown toggle button. */
+  buttonClassName?: string;
+  /** A class name to apply to the dropdown menu. */
+  menuClassName?: string;
+  /** The name of an icon to show in the dropdown toggle button. */
+  icon?: string;
+  /** The name of an icon to show on the right of the button. */
+  caretIcon?: string;
+  /** The label of the dropdown toggle button. Defaults to 'Controls'. */
+  label: Mithril.Children;
+  /** The label used to describe the dropdown toggle button to assistive readers. Defaults to 'Toggle dropdown menu'. */
+  accessibleToggleLabel?: string;
+  /** An action to take when the dropdown is collapsed. */
+  onhide?: () => void;
+  /** An action to take when the dropdown is opened. */
+  onshow?: () => void;
+
+  lazyDraw?: boolean;
+}
+
+/**
+ * The `Dropdown` component displays a button which, when clicked, shows a
+ * dropdown menu beneath it.
+ *
+ * The children will be displayed as a list inside the dropdown menu.
+ */
+export default class Dropdown<CustomAttrs extends IDropdownAttrs = IDropdownAttrs> extends Component<CustomAttrs> {
+  protected showing = false;
+
+  static initAttrs(attrs: IDropdownAttrs) {
+    attrs.className ||= '';
+    attrs.buttonClassName ||= '';
+    attrs.menuClassName ||= '';
+    attrs.label ||= '';
+    attrs.caretIcon ??= 'fas fa-caret-down';
+    attrs.accessibleToggleLabel ||= extractText(app.translator.trans('core.lib.dropdown.toggle_dropdown_accessible_label'));
+  }
+
+  view(vnode: Mithril.Vnode<CustomAttrs, this>) {
+    const items = vnode.children ? listItems(vnode.children as ModdedChildrenWithItemName[]) : [];
+    const renderItems = this.attrs.lazyDraw ? this.showing : true;
+
+    return (
+      <div className={'ButtonGroup Dropdown dropdown ' + this.attrs.className + ' itemCount' + items.length + (this.showing ? ' open' : '')}>
+        {this.getButton(vnode.children as Mithril.ChildArray)}
+        {renderItems && this.getMenu(items)}
+      </div>
+    );
+  }
+
+  oncreate(vnode: Mithril.VnodeDOM<CustomAttrs, this>) {
+    super.oncreate(vnode);
+
+    // When opening the dropdown menu, work out if the menu goes beyond the
+    // bottom of the viewport. If it does, we will apply class to make it show
+    // above the toggle button instead of below it.
+    this.$().on('shown.bs.dropdown', () => {
+      const { lazyDraw, onshow } = this.attrs;
+
+      this.showing = true;
+
+      // If using lazy drawing, redraw before calling `onshow` function
+      // to make sure the menu DOM exists in case the callback tries to use it.
+      if (lazyDraw) {
+        m.redraw.sync();
+      }
+
+      if (typeof onshow === 'function') {
+        onshow();
+      }
+
+      // If not using lazy drawing, keep previous functionality
+      // of redrawing after calling onshow()
+      if (!lazyDraw) {
+        m.redraw();
+      }
+
+      const $menu = this.$('.Dropdown-menu');
+      const isRight = $menu.hasClass('Dropdown-menu--right');
+
+      const top = $menu.offset()?.top ?? 0;
+      const height = $menu.height() ?? 0;
+      const windowSrollTop = $(window).scrollTop() ?? 0;
+      const windowHeight = $(window).height() ?? 0;
+
+      $menu.removeClass('Dropdown-menu--top Dropdown-menu--right');
+
+      $menu.toggleClass('Dropdown-menu--top', top + height > windowSrollTop + windowHeight);
+
+      if (($menu.offset()?.top || 0) < 0) {
+        $menu.removeClass('Dropdown-menu--top');
+      }
+
+      const left = $menu.offset()?.left ?? 0;
+      const width = $menu.width() ?? 0;
+      const windowScrollLeft = $(window).scrollLeft() ?? 0;
+      const windowWidth = $(window).width() ?? 0;
+
+      $menu.toggleClass('Dropdown-menu--right', isRight || left + width > windowScrollLeft + windowWidth);
+    });
+
+    this.$().on('hidden.bs.dropdown', () => {
+      this.showing = false;
+
+      if (this.attrs.onhide) {
+        this.attrs.onhide();
+      }
+
+      m.redraw();
+    });
+  }
+
+  /**
+   * Get the template for the button.
+   */
+  getButton(children: Mithril.ChildArray): Mithril.Vnode<any, any> {
+    return (
+      <button
+        className={'Dropdown-toggle ' + this.attrs.buttonClassName}
+        aria-haspopup="menu"
+        aria-label={this.attrs.accessibleToggleLabel}
+        data-toggle="dropdown"
+        onclick={this.attrs.onclick}
+      >
+        {this.getButtonContent(children)}
+      </button>
+    );
+  }
+
+  /**
+   * Get the template for the button's content.
+   */
+  getButtonContent(children: Mithril.ChildArray): Mithril.ChildArray {
+    return [
+      this.attrs.icon ? icon(this.attrs.icon, { className: 'Button-icon' }) : '',
+      <span className="Button-label">{this.attrs.label}</span>,
+      this.attrs.caretIcon ? icon(this.attrs.caretIcon, { className: 'Button-caret' }) : '',
+    ];
+  }
+
+  getMenu(items: Mithril.Vnode<any, any>[]): Mithril.Vnode<any, any> {
+    return <ul className={'Dropdown-menu dropdown-menu ' + this.attrs.menuClassName}>{items}</ul>;
+  }
+}
diff --git a/framework/core/js/src/common/components/Navigation.tsx b/framework/core/js/src/common/components/Navigation.tsx
index de2cb3e2a..f4e687950 100644
--- a/framework/core/js/src/common/components/Navigation.tsx
+++ b/framework/core/js/src/common/components/Navigation.tsx
@@ -47,7 +47,7 @@ export default class Navigation extends Component {
       icon: 'fas fa-chevron-left',
       'aria-label': previous?.title,
       onclick: (e: MouseEvent) => {
-        if (e.shiftKey || e.ctrlKey || e.metaKey || e.which === 2) return;
+        if (e.shiftKey || e.ctrlKey || e.metaKey || e.button === 1) return;
         e.preventDefault();
         history?.back();
       },
diff --git a/framework/core/js/src/common/components/SelectDropdown.js b/framework/core/js/src/common/components/SelectDropdown.js
deleted file mode 100644
index e7111ffe7..000000000
--- a/framework/core/js/src/common/components/SelectDropdown.js
+++ /dev/null
@@ -1,52 +0,0 @@
-import Dropdown from './Dropdown';
-import icon from '../helpers/icon';
-
-/**
- * Determines via a vnode is currently "active".
- * Due to changes in Mithril 2, attrs will not be instantiated until AFTER view()
- * is initially called on the parent component, so we can not always depend on the
- * active attr to determine which element should be displayed as the "active child".
- *
- * This is a temporary patch, and as so, is not exported / placed in utils.
- */
-function isActive(vnode) {
-  const tag = vnode.tag;
-
-  // Allow non-selectable dividers/headers to be added.
-  if (typeof tag === 'string' && tag !== 'a' && tag !== 'button') return false;
-
-  if ('initAttrs' in tag) {
-    tag.initAttrs(vnode.attrs);
-  }
-
-  return 'isActive' in tag ? tag.isActive(vnode.attrs) : vnode.attrs.active;
-}
-
-/**
- * The `SelectDropdown` component is the same as a `Dropdown`, except the toggle
- * button's label is set as the label of the first child which has a truthy
- * `active` prop.
- *
- * ### Attrs
- *
- * - `caretIcon`
- * - `defaultLabel`
- */
-export default class SelectDropdown extends Dropdown {
-  static initAttrs(attrs) {
-    attrs.caretIcon = typeof attrs.caretIcon !== 'undefined' ? attrs.caretIcon : 'fas fa-sort';
-
-    super.initAttrs(attrs);
-
-    attrs.className += ' Dropdown--select';
-  }
-
-  getButtonContent(children) {
-    const activeChild = children.find(isActive);
-    let label = (activeChild && activeChild.children) || this.attrs.defaultLabel;
-
-    if (label instanceof Array) label = label[0];
-
-    return [<span className="Button-label">{label}</span>, icon(this.attrs.caretIcon, { className: 'Button-caret' })];
-  }
-}
diff --git a/framework/core/js/src/common/components/SelectDropdown.tsx b/framework/core/js/src/common/components/SelectDropdown.tsx
new file mode 100644
index 000000000..66c66fef5
--- /dev/null
+++ b/framework/core/js/src/common/components/SelectDropdown.tsx
@@ -0,0 +1,57 @@
+import Dropdown, { IDropdownAttrs } from './Dropdown';
+import icon from '../helpers/icon';
+import extractText from '../utils/extractText';
+import classList from '../utils/classList';
+import type Component from '../Component';
+import type Mithril from 'mithril';
+
+/**
+ * Determines via a vnode is currently "active".
+ * Due to changes in Mithril 2, attrs will not be instantiated until AFTER view()
+ * is initially called on the parent component, so we can not always depend on the
+ * active attr to determine which element should be displayed as the "active child".
+ *
+ * This is a temporary patch, and as so, is not exported / placed in utils.
+ */
+function isActive(vnode: Mithril.Children): boolean {
+  if (!vnode || typeof vnode !== 'object' || vnode instanceof Array) return false;
+
+  const tag = vnode.tag;
+
+  // Allow non-selectable dividers/headers to be added.
+  if (typeof tag === 'string' && tag !== 'a' && tag !== 'button') return false;
+
+  if (typeof tag === 'object' && 'initAttrs' in tag) {
+    (tag as unknown as typeof Component).initAttrs(vnode.attrs);
+  }
+
+  return typeof tag === 'object' && 'isActive' in tag ? (tag as any).isActive(vnode.attrs) : vnode.attrs.active;
+}
+
+export interface ISelectDropdownAttrs extends IDropdownAttrs {
+  defaultLabel: string;
+}
+
+/**
+ * The `SelectDropdown` component is the same as a `Dropdown`, except the toggle
+ * button's label is set as the label of the first child which has a truthy
+ * `active` prop.
+ */
+export default class SelectDropdown<CustomAttrs extends ISelectDropdownAttrs = ISelectDropdownAttrs> extends Dropdown<CustomAttrs> {
+  static initAttrs(attrs: ISelectDropdownAttrs) {
+    attrs.caretIcon ??= 'fas fa-sort';
+
+    super.initAttrs(attrs);
+
+    attrs.className = classList(attrs.className, 'Dropdown--select');
+  }
+
+  getButtonContent(children: Mithril.ChildArray): Mithril.ChildArray {
+    const activeChild = children.find(isActive);
+    let label = (activeChild && typeof activeChild === 'object' && 'children' in activeChild && activeChild.children) || this.attrs.defaultLabel;
+
+    label = extractText(label);
+
+    return [<span className="Button-label">{label}</span>, this.attrs.caretIcon ? icon(this.attrs.caretIcon, { className: 'Button-caret' }) : null];
+  }
+}
diff --git a/framework/core/js/src/common/components/SplitDropdown.js b/framework/core/js/src/common/components/SplitDropdown.js
deleted file mode 100644
index fea79e6af..000000000
--- a/framework/core/js/src/common/components/SplitDropdown.js
+++ /dev/null
@@ -1,54 +0,0 @@
-import Dropdown from './Dropdown';
-import Button from './Button';
-import icon from '../helpers/icon';
-
-/**
- * The `SplitDropdown` component is similar to `Dropdown`, but the first child
- * is displayed as its own button prior to the toggle button.
- */
-export default class SplitDropdown extends Dropdown {
-  static initAttrs(attrs) {
-    super.initAttrs(attrs);
-
-    attrs.className += ' Dropdown--split';
-    attrs.menuClassName += ' Dropdown-menu--right';
-  }
-
-  getButton(children) {
-    // Make a copy of the attrs of the first child component. We will assign
-    // these attrs to a new button, so that it has exactly the same behaviour as
-    // the first child.
-    const firstChild = this.getFirstChild(children);
-    const buttonAttrs = Object.assign({}, firstChild.attrs);
-    buttonAttrs.className = (buttonAttrs.className || '') + ' SplitDropdown-button Button ' + this.attrs.buttonClassName;
-
-    return [
-      Button.component(buttonAttrs, firstChild.children),
-      <button
-        className={'Dropdown-toggle Button Button--icon ' + this.attrs.buttonClassName}
-        aria-haspopup="menu"
-        aria-label={this.attrs.accessibleToggleLabel}
-        data-toggle="dropdown"
-      >
-        {icon(this.attrs.icon, { className: 'Button-icon' })}
-        {icon('fas fa-caret-down', { className: 'Button-caret' })}
-      </button>,
-    ];
-  }
-
-  /**
-   * Get the first child. If the first child is an array, the first item in that
-   * array will be returned.
-   *
-   * @param {unknown[] | unknown} children
-   * @return {unknown}
-   * @protected
-   */
-  getFirstChild(children) {
-    let firstChild = children;
-
-    while (firstChild instanceof Array) firstChild = firstChild[0];
-
-    return firstChild;
-  }
-}
diff --git a/framework/core/js/src/common/components/SplitDropdown.tsx b/framework/core/js/src/common/components/SplitDropdown.tsx
new file mode 100644
index 000000000..c9e5e3122
--- /dev/null
+++ b/framework/core/js/src/common/components/SplitDropdown.tsx
@@ -0,0 +1,56 @@
+import Dropdown, { IDropdownAttrs } from './Dropdown';
+import Button from './Button';
+import icon from '../helpers/icon';
+import Mithril from 'mithril';
+import classList from '../utils/classList';
+
+export interface ISplitDropdownAttrs extends IDropdownAttrs {}
+
+/**
+ * The `SplitDropdown` component is similar to `Dropdown`, but the first child
+ * is displayed as its own button prior to the toggle button.
+ */
+export default class SplitDropdown extends Dropdown {
+  static initAttrs(attrs: ISplitDropdownAttrs) {
+    super.initAttrs(attrs);
+
+    attrs.className = classList(attrs.className, 'Dropdown--split');
+    attrs.menuClassName = classList(attrs.menuClassName, 'Dropdown-menu--right');
+  }
+
+  getButton(children: Mithril.ChildArray): Mithril.Vnode<any, any> {
+    // Make a copy of the attrs of the first child component. We will assign
+    // these attrs to a new button, so that it has exactly the same behaviour as
+    // the first child.
+    const firstChild = this.getFirstChild(children);
+    const buttonAttrs = Object.assign({}, firstChild?.attrs);
+    buttonAttrs.className = classList(buttonAttrs.className, 'SplitDropdown-button Button', this.attrs.buttonClassName);
+
+    return (
+      <>
+        {Button.component(buttonAttrs, firstChild.children)}
+        <button
+          className={'Dropdown-toggle Button Button--icon ' + this.attrs.buttonClassName}
+          aria-haspopup="menu"
+          aria-label={this.attrs.accessibleToggleLabel}
+          data-toggle="dropdown"
+        >
+          {this.attrs.icon ? icon(this.attrs.icon, { className: 'Button-icon' }) : null}
+          {icon('fas fa-caret-down', { className: 'Button-caret' })}
+        </button>
+      </>
+    );
+  }
+
+  /**
+   * Get the first child. If the first child is an array, the first item in that
+   * array will be returned.
+   */
+  protected getFirstChild(children: Mithril.Children): Mithril.Vnode<any, any> {
+    let firstChild = children;
+
+    while (firstChild instanceof Array) firstChild = firstChild[0];
+
+    return firstChild as Mithril.Vnode<any, any>;
+  }
+}
diff --git a/framework/core/js/src/forum/ForumApplication.ts b/framework/core/js/src/forum/ForumApplication.ts
index e5329b33b..f53baa252 100644
--- a/framework/core/js/src/forum/ForumApplication.ts
+++ b/framework/core/js/src/forum/ForumApplication.ts
@@ -126,7 +126,7 @@ export default class ForumApplication extends Application {
     // Route the home link back home when clicked. We do not want it to register
     // if the user is opening it in a new tab, however.
     document.getElementById('home-link')!.addEventListener('click', (e) => {
-      if (e.ctrlKey || e.metaKey || e.which === 2) return;
+      if (e.ctrlKey || e.metaKey || e.button === 1) return;
       e.preventDefault();
       app.history.home();
 
diff --git a/framework/core/js/src/forum/components/NotificationsDropdown.js b/framework/core/js/src/forum/components/NotificationsDropdown.tsx
similarity index 51%
rename from framework/core/js/src/forum/components/NotificationsDropdown.js
rename to framework/core/js/src/forum/components/NotificationsDropdown.tsx
index 6ec3bc3f0..c295f76bd 100644
--- a/framework/core/js/src/forum/components/NotificationsDropdown.js
+++ b/framework/core/js/src/forum/components/NotificationsDropdown.tsx
@@ -1,26 +1,31 @@
 import app from '../../forum/app';
-import Dropdown from '../../common/components/Dropdown';
+import Dropdown, { IDropdownAttrs } from '../../common/components/Dropdown';
 import icon from '../../common/helpers/icon';
 import classList from '../../common/utils/classList';
 import NotificationList from './NotificationList';
+import extractText from '../../common/utils/extractText';
+import type Mithril from 'mithril';
 
-export default class NotificationsDropdown extends Dropdown {
-  static initAttrs(attrs) {
-    attrs.className = attrs.className || 'NotificationsDropdown';
-    attrs.buttonClassName = attrs.buttonClassName || 'Button Button--flat';
-    attrs.menuClassName = attrs.menuClassName || 'Dropdown-menu--right';
-    attrs.label = attrs.label || app.translator.trans('core.forum.notifications.tooltip');
-    attrs.icon = attrs.icon || 'fas fa-bell';
+export interface INotificationsDropdown extends IDropdownAttrs {}
+
+export default class NotificationsDropdown<CustomAttrs extends IDropdownAttrs = IDropdownAttrs> extends Dropdown<CustomAttrs> {
+  static initAttrs(attrs: INotificationsDropdown) {
+    attrs.className ||= 'NotificationsDropdown';
+    attrs.buttonClassName ||= 'Button Button--flat';
+    attrs.menuClassName ||= 'Dropdown-menu--right';
+    attrs.label ||= extractText(app.translator.trans('core.forum.notifications.tooltip'));
+    attrs.icon ||= 'fas fa-bell';
 
     // For best a11y support, both `title` and `aria-label` should be used
-    attrs.accessibleToggleLabel = attrs.accessibleToggleLabel || app.translator.trans('core.forum.notifications.toggle_dropdown_accessible_label');
+    attrs.accessibleToggleLabel ||= extractText(app.translator.trans('core.forum.notifications.toggle_dropdown_accessible_label'));
 
     super.initAttrs(attrs);
   }
 
-  getButton() {
+  getButton(children: Mithril.ChildArray): Mithril.Vnode<any, any> {
     const newNotifications = this.getNewCount();
-    const vdom = super.getButton();
+
+    const vdom = super.getButton(children);
 
     vdom.attrs.title = this.attrs.label;
 
@@ -30,11 +35,11 @@ export default class NotificationsDropdown extends Dropdown {
     return vdom;
   }
 
-  getButtonContent() {
+  getButtonContent(): Mithril.ChildArray {
     const unread = this.getUnreadCount();
 
     return [
-      icon(this.attrs.icon, { className: 'Button-icon' }),
+      this.attrs.icon ? icon(this.attrs.icon, { className: 'Button-icon' }) : null,
       unread !== 0 && <span className="NotificationsDropdown-unread">{unread}</span>,
       <span className="Button-label">{this.attrs.label}</span>,
     ];
@@ -61,16 +66,16 @@ export default class NotificationsDropdown extends Dropdown {
   }
 
   getUnreadCount() {
-    return app.session.user.unreadNotificationCount();
+    return app.session.user!.unreadNotificationCount();
   }
 
   getNewCount() {
-    return app.session.user.newNotificationCount();
+    return app.session.user!.newNotificationCount();
   }
 
-  menuClick(e) {
+  menuClick(e: MouseEvent) {
     // Don't close the notifications dropdown if the user is opening a link in a
     // new tab or window.
-    if (e.shiftKey || e.metaKey || e.ctrlKey || e.which === 2) e.stopPropagation();
+    if (e.shiftKey || e.metaKey || e.ctrlKey || e.button === 1) e.stopPropagation();
   }
 }
diff --git a/framework/core/js/src/forum/components/SessionDropdown.js b/framework/core/js/src/forum/components/SessionDropdown.tsx
similarity index 75%
rename from framework/core/js/src/forum/components/SessionDropdown.js
rename to framework/core/js/src/forum/components/SessionDropdown.tsx
index 456069cd2..5657b1439 100644
--- a/framework/core/js/src/forum/components/SessionDropdown.js
+++ b/framework/core/js/src/forum/components/SessionDropdown.tsx
@@ -1,28 +1,32 @@
 import app from '../../forum/app';
 import avatar from '../../common/helpers/avatar';
 import username from '../../common/helpers/username';
-import Dropdown from '../../common/components/Dropdown';
+import Dropdown, { IDropdownAttrs } from '../../common/components/Dropdown';
 import LinkButton from '../../common/components/LinkButton';
 import Button from '../../common/components/Button';
 import ItemList from '../../common/utils/ItemList';
 import Separator from '../../common/components/Separator';
+import extractText from '../../common/utils/extractText';
+import type Mithril from 'mithril';
+
+export interface ISessionDropdownAttrs extends IDropdownAttrs {}
 
 /**
  * The `SessionDropdown` component shows a button with the current user's
  * avatar/name, with a dropdown of session controls.
  */
-export default class SessionDropdown extends Dropdown {
-  static initAttrs(attrs) {
+export default class SessionDropdown<CustomAttrs extends ISessionDropdownAttrs = ISessionDropdownAttrs> extends Dropdown<CustomAttrs> {
+  static initAttrs(attrs: ISessionDropdownAttrs) {
     super.initAttrs(attrs);
 
     attrs.className = 'SessionDropdown';
     attrs.buttonClassName = 'Button Button--user Button--flat';
     attrs.menuClassName = 'Dropdown-menu--right';
 
-    attrs.accessibleToggleLabel = app.translator.trans('core.forum.header.session_dropdown_accessible_label');
+    attrs.accessibleToggleLabel = extractText(app.translator.trans('core.forum.header.session_dropdown_accessible_label'));
   }
 
-  view(vnode) {
+  view(vnode: Mithril.Vnode<CustomAttrs, this>) {
     return super.view({ ...vnode, children: this.items().toArray() });
   }
 
@@ -34,12 +38,10 @@ export default class SessionDropdown extends Dropdown {
 
   /**
    * Build an item list for the contents of the dropdown menu.
-   *
-   * @return {ItemList<import('mithril').Children>}
    */
-  items() {
-    const items = new ItemList();
-    const user = app.session.user;
+  items(): ItemList<Mithril.Children> {
+    const items = new ItemList<Mithril.Children>();
+    const user = app.session.user!;
 
     items.add(
       'profile',