diff --git a/resources/celerity/map.php b/resources/celerity/map.php
--- a/resources/celerity/map.php
+++ b/resources/celerity/map.php
@@ -7,8 +7,8 @@
  */
 return array(
   'names' => array(
-    'core.pkg.css' => 'b9e2e1e5',
-    'core.pkg.js' => '80f86a0a',
+    'core.pkg.css' => 'f577cd20',
+    'core.pkg.js' => 'f2139810',
     'darkconsole.pkg.js' => 'e7393ebb',
     'differential.pkg.css' => 'b3eea3f5',
     'differential.pkg.js' => '4b7d8f19',
@@ -124,7 +124,7 @@
     'rsrc/css/phui/phui-badge.css' => '3baef8db',
     'rsrc/css/phui/phui-big-info-view.css' => 'bd903741',
     'rsrc/css/phui/phui-box.css' => '5c8387cf',
-    'rsrc/css/phui/phui-button.css' => 'a64a8de6',
+    'rsrc/css/phui/phui-button.css' => 'e266e0bc',
     'rsrc/css/phui/phui-chart.css' => '6bf6f78e',
     'rsrc/css/phui/phui-crumbs-view.css' => '6b813619',
     'rsrc/css/phui/phui-curtain-view.css' => '7148ae25',
@@ -516,14 +516,15 @@
     'rsrc/js/core/behavior-watch-anchor.js' => '9f36c42d',
     'rsrc/js/core/behavior-workflow.js' => '0a3f3021',
     'rsrc/js/core/phtize.js' => 'd254d646',
-    'rsrc/js/phui/behavior-phui-dropdown-menu.js' => '54733475',
+    'rsrc/js/phui/behavior-phui-dropdown-menu.js' => '1aa4c968',
     'rsrc/js/phui/behavior-phui-file-upload.js' => 'b003d4fb',
     'rsrc/js/phui/behavior-phui-object-box-tabs.js' => '2bfa2836',
     'rsrc/js/phui/behavior-phui-profile-menu.js' => '12884df9',
+    'rsrc/js/phui/behavior-phui-submenu.js' => 'a6f7a73b',
     'rsrc/js/phuix/PHUIXActionListView.js' => 'b5c256b8',
     'rsrc/js/phuix/PHUIXActionView.js' => '8cf6d262',
     'rsrc/js/phuix/PHUIXAutocomplete.js' => '9196fb06',
-    'rsrc/js/phuix/PHUIXDropdownMenu.js' => 'bd4c8dca',
+    'rsrc/js/phuix/PHUIXDropdownMenu.js' => '82e270da',
     'rsrc/js/phuix/PHUIXFormControl.js' => 'e15869a8',
     'rsrc/js/phuix/PHUIXIconView.js' => 'bff6884b',
   ),
@@ -669,11 +670,12 @@
     'javelin-behavior-phabricator-watch-anchor' => '9f36c42d',
     'javelin-behavior-pholio-mock-edit' => 'bee502c8',
     'javelin-behavior-pholio-mock-view' => 'fbe497e7',
-    'javelin-behavior-phui-dropdown-menu' => '54733475',
+    'javelin-behavior-phui-dropdown-menu' => '1aa4c968',
     'javelin-behavior-phui-file-upload' => 'b003d4fb',
     'javelin-behavior-phui-hovercards' => 'bcaccd64',
     'javelin-behavior-phui-object-box-tabs' => '2bfa2836',
     'javelin-behavior-phui-profile-menu' => '12884df9',
+    'javelin-behavior-phui-submenu' => 'a6f7a73b',
     'javelin-behavior-policy-control' => 'd0c516d5',
     'javelin-behavior-policy-rule-editor' => '5e9f347c',
     'javelin-behavior-project-boards' => '14a1faae',
@@ -822,7 +824,7 @@
     'phui-badge-view-css' => '3baef8db',
     'phui-big-info-view-css' => 'bd903741',
     'phui-box-css' => '5c8387cf',
-    'phui-button-css' => 'a64a8de6',
+    'phui-button-css' => 'e266e0bc',
     'phui-calendar-css' => 'ccabe893',
     'phui-calendar-day-css' => 'd1cf6f93',
     'phui-calendar-list-css' => '56e6381a',
@@ -870,7 +872,7 @@
     'phuix-action-list-view' => 'b5c256b8',
     'phuix-action-view' => '8cf6d262',
     'phuix-autocomplete' => '9196fb06',
-    'phuix-dropdown-menu' => 'bd4c8dca',
+    'phuix-dropdown-menu' => '82e270da',
     'phuix-form-control-view' => 'e15869a8',
     'phuix-icon-view' => 'bff6884b',
     'policy-css' => '957ea14c',
@@ -1024,6 +1026,12 @@
       'javelin-workflow',
       'javelin-workboard-controller',
     ),
+    '1aa4c968' => array(
+      'javelin-behavior',
+      'javelin-stratcom',
+      'javelin-dom',
+      'phuix-dropdown-menu',
+    ),
     '1ad0a787' => array(
       'javelin-install',
       'javelin-reactor',
@@ -1275,12 +1283,6 @@
       'javelin-leader',
       'javelin-json',
     ),
-    54733475 => array(
-      'javelin-behavior',
-      'javelin-stratcom',
-      'javelin-dom',
-      'phuix-dropdown-menu',
-    ),
     '54b612ba' => array(
       'javelin-color',
       'javelin-install',
@@ -1529,6 +1531,13 @@
       'javelin-vector',
       'javelin-stratcom',
     ),
+    '82e270da' => array(
+      'javelin-install',
+      'javelin-util',
+      'javelin-dom',
+      'javelin-vector',
+      'javelin-stratcom',
+    ),
     '834a1173' => array(
       'javelin-behavior',
       'javelin-scrollbar',
@@ -1693,6 +1702,11 @@
       'javelin-uri',
       'phabricator-notification',
     ),
+    'a6f7a73b' => array(
+      'javelin-behavior',
+      'javelin-stratcom',
+      'javelin-dom',
+    ),
     'a80d0378' => array(
       'javelin-behavior',
       'javelin-stratcom',
@@ -1846,13 +1860,6 @@
       'javelin-vector',
       'phui-hovercard',
     ),
-    'bd4c8dca' => array(
-      'javelin-install',
-      'javelin-util',
-      'javelin-dom',
-      'javelin-vector',
-      'javelin-stratcom',
-    ),
     'bdaf4d04' => array(
       'javelin-behavior',
       'javelin-dom',
diff --git a/src/applications/base/controller/PhabricatorController.php b/src/applications/base/controller/PhabricatorController.php
--- a/src/applications/base/controller/PhabricatorController.php
+++ b/src/applications/base/controller/PhabricatorController.php
@@ -474,8 +474,11 @@
   public function newCurtainView($object) {
     $viewer = $this->getViewer();
 
+    $action_id = celerity_generate_unique_node_id();
+
     $action_list = id(new PhabricatorActionListView())
-      ->setViewer($viewer);
+      ->setViewer($viewer)
+      ->setID($action_id);
 
     // NOTE: Applications (objects of class PhabricatorApplication) can't
     // currently be set here, although they don't need any of the extensions
diff --git a/src/applications/maniphest/controller/ManiphestTaskDetailController.php b/src/applications/maniphest/controller/ManiphestTaskDetailController.php
--- a/src/applications/maniphest/controller/ManiphestTaskDetailController.php
+++ b/src/applications/maniphest/controller/ManiphestTaskDetailController.php
@@ -166,15 +166,6 @@
         ->setDisabled(!$can_edit)
         ->setWorkflow(!$can_edit));
 
-    $curtain->addAction(
-      id(new PhabricatorActionView())
-        ->setName(pht('Merge Duplicates In'))
-        ->setHref("/search/attach/{$phid}/TASK/merge/")
-        ->setWorkflow(true)
-        ->setIcon('fa-compress')
-        ->setDisabled(!$can_edit)
-        ->setWorkflow(true));
-
     $edit_config = $edit_engine->loadDefaultEditConfiguration();
     $can_create = (bool)$edit_config;
 
@@ -195,23 +186,36 @@
       $edit_uri = $this->getApplicationURI($edit_uri);
     }
 
-    $curtain->addAction(
-      id(new PhabricatorActionView())
-        ->setName(pht('Create Subtask'))
-        ->setHref($edit_uri)
-        ->setIcon('fa-level-down')
-        ->setDisabled(!$can_create)
-        ->setWorkflow(!$can_create));
+    $task_submenu = array();
+
+    $task_submenu[] = id(new PhabricatorActionView())
+      ->setName(pht('Create Subtask'))
+      ->setHref($edit_uri)
+      ->setIcon('fa-level-down')
+      ->setDisabled(!$can_create)
+      ->setWorkflow(!$can_create);
+
+    $task_submenu[] = id(new PhabricatorActionView())
+      ->setName(pht('Edit Blocking Tasks'))
+      ->setHref("/search/attach/{$phid}/TASK/blocks/")
+      ->setWorkflow(true)
+      ->setIcon('fa-link')
+      ->setDisabled(!$can_edit)
+      ->setWorkflow(true);
+
+    $task_submenu[] = id(new PhabricatorActionView())
+      ->setName(pht('Merge Duplicates In'))
+      ->setHref("/search/attach/{$phid}/TASK/merge/")
+      ->setWorkflow(true)
+      ->setIcon('fa-compress')
+      ->setDisabled(!$can_edit)
+      ->setWorkflow(true);
 
     $curtain->addAction(
       id(new PhabricatorActionView())
-        ->setName(pht('Edit Blocking Tasks'))
-        ->setHref("/search/attach/{$phid}/TASK/blocks/")
-        ->setWorkflow(true)
-        ->setIcon('fa-link')
-        ->setDisabled(!$can_edit)
-        ->setWorkflow(true));
-
+        ->setName(pht('Edit Related Tasks...'))
+        ->setIcon('fa-anchor')
+        ->setSubmenu($task_submenu));
 
     $owner_phid = $task->getOwnerPHID();
     $author_phid = $task->getAuthorPHID();
diff --git a/src/view/layout/PhabricatorActionListView.php b/src/view/layout/PhabricatorActionListView.php
--- a/src/view/layout/PhabricatorActionListView.php
+++ b/src/view/layout/PhabricatorActionListView.php
@@ -21,6 +21,10 @@
     return $this;
   }
 
+  public function getID() {
+    return $this->id;
+  }
+
   public function render() {
     $viewer = $this->getViewer();
 
@@ -44,13 +48,20 @@
 
     require_celerity_resource('phabricator-action-list-view-css');
 
+    $items = array();
+    foreach ($actions as $action) {
+      foreach ($action->getItems() as $item) {
+        $items[] = $item;
+      }
+    }
+
     return phutil_tag(
       'ul',
       array(
         'class' => 'phabricator-action-list-view',
         'id' => $this->id,
       ),
-      $actions);
+      $items);
   }
 
   public function getDropdownMenuMetadata() {
diff --git a/src/view/layout/PhabricatorActionView.php b/src/view/layout/PhabricatorActionView.php
--- a/src/view/layout/PhabricatorActionView.php
+++ b/src/view/layout/PhabricatorActionView.php
@@ -14,6 +14,10 @@
   private $metadata;
   private $selected;
   private $openInNewWindow;
+  private $submenu = array();
+  private $hidden;
+  private $depth;
+  private $id;
 
   public function setSelected($selected) {
     $this->selected = $selected;
@@ -95,7 +99,60 @@
     return $this->openInNewWindow;
   }
 
+  public function getID() {
+    if (!$this->id) {
+      $this->id = celerity_generate_unique_node_id();
+    }
+    return $this->id;
+  }
+
+  public function setSubmenu(array $submenu) {
+    $this->submenu = $submenu;
+
+    if (!$this->getHref()) {
+      $this->setHref('#');
+    }
+
+    return $this;
+  }
+
+  public function getItems($depth = 0) {
+    $items = array();
+
+    $items[] = $this;
+    foreach ($this->submenu as $action) {
+      foreach ($action->getItems($depth + 1) as $item) {
+        $item
+          ->setHidden(true)
+          ->setDepth($depth + 1);
+
+        $items[] = $item;
+      }
+    }
+
+    return $items;
+  }
+
+  public function setHidden($hidden) {
+    $this->hidden = $hidden;
+    return $this;
+  }
+
+  public function getHidden() {
+    return $this->hidden;
+  }
+
+  public function setDepth($depth) {
+    $this->depth = $depth;
+    return $this;
+  }
+
+  public function getDepth() {
+    return $this->depth;
+  }
+
   public function render() {
+    $caret_id = celerity_generate_unique_node_id();
 
     $icon = null;
     if ($this->icon) {
@@ -155,6 +212,18 @@
           $target = null;
         }
 
+        if ($this->submenu) {
+          $caret = javelin_tag(
+            'span',
+            array(
+              'class' => 'caret-right',
+              'id' => $caret_id,
+            ),
+            '');
+        } else {
+          $caret = null;
+        }
+
         $item = javelin_tag(
           'a',
           array(
@@ -164,7 +233,7 @@
             'sigil' => $sigils,
             'meta' => $this->metadata,
           ),
-          array($icon, $this->name));
+          array($icon, $this->name, $caret));
       }
     } else {
       $item = phutil_tag(
@@ -190,10 +259,47 @@
       $classes[] = 'phabricator-action-view-selected';
     }
 
-    return phutil_tag(
+    if ($this->submenu) {
+      $classes[] = 'phabricator-action-view-submenu';
+    }
+
+    $style = array();
+
+    if ($this->hidden) {
+      $style[] = 'display: none;';
+    }
+
+    if ($this->depth) {
+      $indent = ($this->depth * 16);
+      $style[] = "margin-left: {$indent}px;";
+    }
+
+    $sigil = null;
+    $meta = null;
+
+    if ($this->submenu) {
+      Javelin::initBehavior('phui-submenu');
+      $sigil = 'phui-submenu';
+
+      $item_ids = array();
+      foreach ($this->submenu as $subitem) {
+        $item_ids[] = $subitem->getID();
+      }
+
+      $meta = array(
+        'itemIDs' => $item_ids,
+        'caretID' => $caret_id,
+      );
+    }
+
+    return javelin_tag(
       'li',
       array(
+        'id' => $this->getID(),
         'class' => implode(' ', $classes),
+        'style' => implode(' ', $style),
+        'sigil' => $sigil,
+        'meta' => $meta,
       ),
       $item);
   }
diff --git a/src/view/phui/PHUIButtonView.php b/src/view/phui/PHUIButtonView.php
--- a/src/view/phui/PHUIButtonView.php
+++ b/src/view/phui/PHUIButtonView.php
@@ -110,6 +110,18 @@
     return $this;
   }
 
+  public function setDropdownMenuID($id) {
+    Javelin::initBehavior('phui-dropdown-menu');
+
+    $this->addSigil('phui-dropdown-menu');
+    $this->setMetadata(
+      array(
+        'menuID' => $id,
+      ));
+
+    return $this;
+  }
+
   protected function getTagAttributes() {
 
     require_celerity_resource('phui-button-css');
diff --git a/src/view/phui/PHUIHeaderView.php b/src/view/phui/PHUIHeaderView.php
--- a/src/view/phui/PHUIHeaderView.php
+++ b/src/view/phui/PHUIHeaderView.php
@@ -24,6 +24,7 @@
   private $badges = array();
   private $href;
   private $actionList;
+  private $actionListID;
 
   public function setHeader($header) {
     $this->header = $header;
@@ -90,6 +91,11 @@
     return $this;
   }
 
+  public function setActionListID($action_list_id) {
+    $this->actionListID = $action_list_id;
+    return $this;
+  }
+
   public function setPolicyObject(PhabricatorPolicyInterface $object) {
     $this->policyObject = $object;
     return $this;
@@ -189,14 +195,20 @@
 
   protected function getTagContent() {
 
-    if ($this->actionList) {
+    if ($this->actionList || $this->actionListID) {
       $action_button = id(new PHUIButtonView())
         ->setTag('a')
         ->setText(pht('Actions'))
         ->setHref('#')
         ->setIcon('fa-bars')
-        ->addClass('phui-mobile-menu')
-        ->setDropdownMenu($this->actionList);
+        ->addClass('phui-mobile-menu');
+
+      if ($this->actionList) {
+        $action_button->setDropdownMenu($this->actionList);
+      } else if ($this->actionListID) {
+        $action_button->setDropdownMenuID($this->actionListID);
+      }
+
       $this->addActionLink($action_button);
     }
 
diff --git a/src/view/phui/PHUITimelineEventView.php b/src/view/phui/PHUITimelineEventView.php
--- a/src/view/phui/PHUITimelineEventView.php
+++ b/src/view/phui/PHUITimelineEventView.php
@@ -327,9 +327,7 @@
           'sigil' => $sigil,
           'aria-haspopup' => 'true',
           'aria-expanded' => 'false',
-          'meta' => array(
-            'items' => hsprintf('%s', $action_list),
-          ),
+          'meta' => $action_list->getDropdownMenuMetadata(),
         ),
         array(
           $aural,
diff --git a/src/view/phui/PHUITwoColumnView.php b/src/view/phui/PHUITwoColumnView.php
--- a/src/view/phui/PHUITwoColumnView.php
+++ b/src/view/phui/PHUITwoColumnView.php
@@ -114,7 +114,7 @@
       $curtain = $this->getCurtain();
       if ($curtain) {
         $action_list = $curtain->getActionList();
-        $this->header->setActionList($action_list);
+        $this->header->setActionListID($action_list->getID());
       }
 
       $header = phutil_tag_div(
diff --git a/webroot/rsrc/css/phui/phui-button.css b/webroot/rsrc/css/phui/phui-button.css
--- a/webroot/rsrc/css/phui/phui-button.css
+++ b/webroot/rsrc/css/phui/phui-button.css
@@ -264,6 +264,42 @@
   border-top-color: #000;
 }
 
+.phabricator-action-view-submenu .caret-right {
+  float: right;
+  margin-top: 4px;
+  margin-right: 6px;
+  border-left-color: {$lightgreytext};
+}
+
+.phabricator-action-view-submenu .caret {
+  float: right;
+  margin-top: 5px;
+  margin-right: 4px;
+  border-top: 7px solid {$lightgreytext};
+}
+
+.phabricator-action-view-submenu.phui-submenu-open {
+  background: {$greybackground};
+}
+
+.phui-submenu-animate {
+  animation: phui-submenu-summon 0.25s;
+}
+
+@keyframes phui-submenu-summon {
+  0% {
+    color: {$lightgreytext};
+    margin-left: 0;
+    transform: rotate(12deg);
+  }
+  60% {
+    margin-left: 24px;
+    transform: rotate(-5deg);
+    margin-top: 18px;
+  }
+}
+
+
 /* Icons */
 .button.has-icon {
   position: relative;
diff --git a/webroot/rsrc/js/phui/behavior-phui-dropdown-menu.js b/webroot/rsrc/js/phui/behavior-phui-dropdown-menu.js
--- a/webroot/rsrc/js/phui/behavior-phui-dropdown-menu.js
+++ b/webroot/rsrc/js/phui/behavior-phui-dropdown-menu.js
@@ -16,17 +16,42 @@
 
     e.kill();
 
-    var list = JX.$H(data.items).getFragment().firstChild;
+    var list;
+    var placeholder;
+    if (data.items) {
+      list = JX.$H(data.items).getFragment().firstChild;
+    } else {
+      list = JX.$(data.menuID);
+      placeholder = JX.$N('span');
+    }
 
     var icon = e.getNode('phui-dropdown-menu');
     data.menu = new JX.PHUIXDropdownMenu(icon);
-    data.menu.setContent(list);
+
+    data.menu.listen('open', function() {
+      if (placeholder) {
+        JX.DOM.replace(list, placeholder);
+      }
+      data.menu.setContent(list);
+    });
+
+    data.menu.listen('close', function() {
+      if (placeholder) {
+        JX.DOM.replace(placeholder, list);
+      }
+    });
+
     data.menu.open();
 
     JX.DOM.listen(list, 'click', 'tag:a', function(e) {
       if (!e.isNormalClick()) {
         return;
       }
+
+      if (JX.Stratcom.pass()) {
+        return;
+      }
+
       data.menu.close();
     });
   });
diff --git a/webroot/rsrc/js/phui/behavior-phui-submenu.js b/webroot/rsrc/js/phui/behavior-phui-submenu.js
new file mode 100644
--- /dev/null
+++ b/webroot/rsrc/js/phui/behavior-phui-submenu.js
@@ -0,0 +1,44 @@
+/**
+ * @provides javelin-behavior-phui-submenu
+ * @requires javelin-behavior
+ *           javelin-stratcom
+ *           javelin-dom
+ */
+
+JX.behavior('phui-submenu', function() {
+
+  JX.Stratcom.listen('click', 'phui-submenu', function(e) {
+    if (!e.isNormalClick()) {
+      return;
+    }
+
+    var node = e.getNode('phui-submenu');
+    var data = e.getNodeData('phui-submenu');
+
+    e.kill();
+
+    data.open = !data.open;
+
+    for (var ii = 0; ii < data.itemIDs.length; ii++) {
+      var id = data.itemIDs[ii];
+      var item = JX.$(id);
+      if (data.open) {
+        JX.DOM.show(item);
+      } else {
+        JX.DOM.hide(item);
+      }
+
+      // Add a class so we can animate zany effects.
+      JX.DOM.alterClass(item, 'phui-submenu-animate', data.open);
+    }
+
+    JX.DOM.alterClass(node, 'phui-submenu-open', data.open);
+
+    // Toggle the caret from ">" to "V" when opening the menu, and back again
+    // when closing it.
+    var caret = JX.$(data.caretID);
+    JX.DOM.alterClass(caret, 'caret', data.open);
+    JX.DOM.alterClass(caret, 'caret-right', !data.open);
+  });
+
+});
diff --git a/webroot/rsrc/js/phuix/PHUIXDropdownMenu.js b/webroot/rsrc/js/phuix/PHUIXDropdownMenu.js
--- a/webroot/rsrc/js/phuix/PHUIXDropdownMenu.js
+++ b/webroot/rsrc/js/phuix/PHUIXDropdownMenu.js
@@ -42,7 +42,7 @@
     JX.Stratcom.listen('keydown', null, JX.bind(this, this._onkey));
   },
 
-  events: ['open'],
+  events: ['open', 'close'],
 
   properties: {
     width: null,
@@ -83,6 +83,8 @@
       this._open = false;
       this._hide();
 
+      this.invoke('close');
+
       return this;
     },