Introduce "Curtain" views, panels, and extensions

Summary:
This opens up the new action column to have specialized rendering and behavior. Briefly:

  - Converted applications (right now, only Paste) render a `CurtainView` to build the column content.
  - This view uses new extensions to build panels (projects, subscribers, tokens).
  - The panel extension code and rendering can be changed without breaking old stuff.

Minor changes:

  - Token awards now load their tokens, for consistency/simplicity.
  - Removed the rest of the "fork of" / "forked from" UI in Paste -- I essentially removed these features a while ago, and no one has complained.

Test Plan:
UI is a bit rough, but works, and it's going to get changed now anyway:

{F1160550}

{F1160551}

Reviewers: chad

Reviewed By: chad

Differential Revision: https://secure.phabricator.com/D15414

resources/celerity/map.php

@@ -127,6 +127,7 @@ return array(
     'rsrc/css/phui/phui-button.css' => 'a64a8de6',
     'rsrc/css/phui/phui-chart.css' => '6bf6f78e',
     'rsrc/css/phui/phui-crumbs-view.css' => '79d536e5',
+    'rsrc/css/phui/phui-curtain-view.css' => '8bb7ee8f',
     'rsrc/css/phui/phui-document-pro.css' => '92d5b648',
     'rsrc/css/phui/phui-document-summary.css' => '9ca48bdf',
     'rsrc/css/phui/phui-document.css' => '9c71d2bf',
@@ -811,6 +812,7 @@ return array(
     'phui-calendar-month-css' => '476be7e0',
     'phui-chart-css' => '6bf6f78e',
     'phui-crumbs-view-css' => '79d536e5',
+    'phui-curtain-view-css' => '8bb7ee8f',
     'phui-document-summary-view-css' => '9ca48bdf',
     'phui-document-view-css' => '9c71d2bf',
     'phui-document-view-pro-css' => '92d5b648',

src/__phutil_library_map__.php

@@ -1505,6 +1505,9 @@ phutil_register_library_map(array(
     'PHUIColorPalletteExample' => 'applications/uiexample/examples/PHUIColorPalletteExample.php',
     'PHUICrumbView' => 'view/phui/PHUICrumbView.php',
     'PHUICrumbsView' => 'view/phui/PHUICrumbsView.php',
+    'PHUICurtainExtension' => 'view/extension/PHUICurtainExtension.php',
+    'PHUICurtainPanelView' => 'view/layout/PHUICurtainPanelView.php',
+    'PHUICurtainView' => 'view/layout/PHUICurtainView.php',
     'PHUIDiffInlineCommentDetailView' => 'infrastructure/diff/view/PHUIDiffInlineCommentDetailView.php',
     'PHUIDiffInlineCommentEditView' => 'infrastructure/diff/view/PHUIDiffInlineCommentEditView.php',
     'PHUIDiffInlineCommentRowScaffold' => 'infrastructure/diff/view/PHUIDiffInlineCommentRowScaffold.php',
@@ -3011,6 +3014,7 @@ phutil_register_library_map(array(
     'PhabricatorProjectWatcherListView' => 'applications/project/view/PhabricatorProjectWatcherListView.php',
     'PhabricatorProjectWorkboardBackgroundColor' => 'applications/project/constants/PhabricatorProjectWorkboardBackgroundColor.php',
     'PhabricatorProjectWorkboardProfilePanel' => 'applications/project/profilepanel/PhabricatorProjectWorkboardProfilePanel.php',
+    'PhabricatorProjectsCurtainExtension' => 'applications/project/engineextension/PhabricatorProjectsCurtainExtension.php',
     'PhabricatorProjectsEditEngineExtension' => 'applications/project/engineextension/PhabricatorProjectsEditEngineExtension.php',
     'PhabricatorProjectsEditField' => 'applications/transactions/editfield/PhabricatorProjectsEditField.php',
     'PhabricatorProjectsFulltextEngineExtension' => 'applications/project/engineextension/PhabricatorProjectsFulltextEngineExtension.php',
@@ -3320,6 +3324,7 @@ phutil_register_library_map(array(
     'PhabricatorSubscriptionsAddSelfHeraldAction' => 'applications/subscriptions/herald/PhabricatorSubscriptionsAddSelfHeraldAction.php',
     'PhabricatorSubscriptionsAddSubscribersHeraldAction' => 'applications/subscriptions/herald/PhabricatorSubscriptionsAddSubscribersHeraldAction.php',
     'PhabricatorSubscriptionsApplication' => 'applications/subscriptions/application/PhabricatorSubscriptionsApplication.php',
+    'PhabricatorSubscriptionsCurtainExtension' => 'applications/subscriptions/engineextension/PhabricatorSubscriptionsCurtainExtension.php',
     'PhabricatorSubscriptionsEditController' => 'applications/subscriptions/controller/PhabricatorSubscriptionsEditController.php',
     'PhabricatorSubscriptionsEditEngineExtension' => 'applications/subscriptions/engineextension/PhabricatorSubscriptionsEditEngineExtension.php',
     'PhabricatorSubscriptionsEditor' => 'applications/subscriptions/editor/PhabricatorSubscriptionsEditor.php',
@@ -3388,6 +3393,7 @@ phutil_register_library_map(array(
     'PhabricatorTokenUIEventListener' => 'applications/tokens/event/PhabricatorTokenUIEventListener.php',
     'PhabricatorTokenizerEditField' => 'applications/transactions/editfield/PhabricatorTokenizerEditField.php',
     'PhabricatorTokensApplication' => 'applications/tokens/application/PhabricatorTokensApplication.php',
+    'PhabricatorTokensCurtainExtension' => 'applications/tokens/engineextension/PhabricatorTokensCurtainExtension.php',
     'PhabricatorTokensSettingsPanel' => 'applications/settings/panel/PhabricatorTokensSettingsPanel.php',
     'PhabricatorTooltipUIExample' => 'applications/uiexample/examples/PhabricatorTooltipUIExample.php',
     'PhabricatorTransactions' => 'applications/transactions/constants/PhabricatorTransactions.php',
@@ -5751,6 +5757,9 @@ phutil_register_library_map(array(
     'PHUIColorPalletteExample' => 'PhabricatorUIExample',
     'PHUICrumbView' => 'AphrontView',
     'PHUICrumbsView' => 'AphrontView',
+    'PHUICurtainExtension' => 'Phobject',
+    'PHUICurtainPanelView' => 'AphrontTagView',
+    'PHUICurtainView' => 'AphrontTagView',
     'PHUIDiffInlineCommentDetailView' => 'PHUIDiffInlineCommentView',
     'PHUIDiffInlineCommentEditView' => 'PHUIDiffInlineCommentView',
     'PHUIDiffInlineCommentRowScaffold' => 'AphrontView',
@@ -7503,6 +7512,7 @@ phutil_register_library_map(array(
     'PhabricatorProjectWatcherListView' => 'PhabricatorProjectUserListView',
     'PhabricatorProjectWorkboardBackgroundColor' => 'Phobject',
     'PhabricatorProjectWorkboardProfilePanel' => 'PhabricatorProfilePanel',
+    'PhabricatorProjectsCurtainExtension' => 'PHUICurtainExtension',
     'PhabricatorProjectsEditEngineExtension' => 'PhabricatorEditEngineExtension',
     'PhabricatorProjectsEditField' => 'PhabricatorTokenizerEditField',
     'PhabricatorProjectsFulltextEngineExtension' => 'PhabricatorFulltextEngineExtension',
@@ -7872,6 +7882,7 @@ phutil_register_library_map(array(
     'PhabricatorSubscriptionsAddSelfHeraldAction' => 'PhabricatorSubscriptionsHeraldAction',
     'PhabricatorSubscriptionsAddSubscribersHeraldAction' => 'PhabricatorSubscriptionsHeraldAction',
     'PhabricatorSubscriptionsApplication' => 'PhabricatorApplication',
+    'PhabricatorSubscriptionsCurtainExtension' => 'PHUICurtainExtension',
     'PhabricatorSubscriptionsEditController' => 'PhabricatorController',
     'PhabricatorSubscriptionsEditEngineExtension' => 'PhabricatorEditEngineExtension',
     'PhabricatorSubscriptionsEditor' => 'PhabricatorEditor',
@@ -7945,6 +7956,7 @@ phutil_register_library_map(array(
     'PhabricatorTokenUIEventListener' => 'PhabricatorEventListener',
     'PhabricatorTokenizerEditField' => 'PhabricatorPHIDListEditField',
     'PhabricatorTokensApplication' => 'PhabricatorApplication',
+    'PhabricatorTokensCurtainExtension' => 'PHUICurtainExtension',
     'PhabricatorTokensSettingsPanel' => 'PhabricatorSettingsPanel',
     'PhabricatorTooltipUIExample' => 'PhabricatorUIExample',
     'PhabricatorTransactions' => 'Phobject',

src/applications/base/controller/PhabricatorController.php

@@ -468,7 +468,26 @@ abstract class PhabricatorController extends AphrontController {
 
   public function newApplicationMenu() {
     return id(new PHUIApplicationMenuView())
-      ->setViewer($this->getRequest()->getUser());
+      ->setViewer($this->getViewer());
+  }
+
+  public function newCurtainView($object) {
+    $viewer = $this->getViewer();
+
+    $action_list = id(new PhabricatorActionListView())
+      ->setViewer($viewer)
+      ->setObject($object);
+
+    $curtain = id(new PHUICurtainView())
+      ->setViewer($viewer)
+      ->setActionList($action_list);
+
+    $panels = PHUICurtainExtension::buildExtensionPanels($viewer, $object);
+    foreach ($panels as $panel) {
+      $curtain->addPanel($panel);
+    }
+
+    return $curtain;
   }
 
   protected function buildTransactionTimeline(

src/applications/paste/controller/PhabricatorPasteViewController.php

@@ -40,15 +40,9 @@ final class PhabricatorPasteViewController extends PhabricatorPasteController {
       return new Aphront404Response();
     }
 
-    $forks = id(new PhabricatorPasteQuery())
-      ->setViewer($viewer)
-      ->withParentPHIDs(array($paste->getPHID()))
-      ->execute();
-    $fork_phids = mpull($forks, 'getPHID');
-
     $header = $this->buildHeaderView($paste);
-    $actions = $this->buildActionView($viewer, $paste);
+    $curtain = $this->buildCurtain($paste);
-    $properties = $this->buildPropertyView($paste, $fork_phids);
+
     $subheader = $this->buildSubheaderView($paste);
     $source_code = $this->buildSourceCodeView($paste, $this->highlightMap);
 
@@ -78,8 +72,7 @@ final class PhabricatorPasteViewController extends PhabricatorPasteController {
           $timeline,
           $comment_view,
         ))
-      ->setPropertyList($properties)
+      ->setCurtain($curtain)
-      ->setActionList($actions)
       ->addClass('ponder-question-view');
 
     return $this->newPage()
@@ -116,9 +109,9 @@ final class PhabricatorPasteViewController extends PhabricatorPasteController {
     return $header;
   }
 
-  private function buildActionView(
+  private function buildCurtain(PhabricatorPaste $paste) {
-    PhabricatorUser $viewer,
+    $viewer = $this->getViewer();
-    PhabricatorPaste $paste) {
+    $curtain = $this->newCurtainView($paste);
 
     $can_edit = PhabricatorPolicyFilter::hasCapability(
       $viewer,
@@ -126,43 +119,42 @@ final class PhabricatorPasteViewController extends PhabricatorPasteController {
       PhabricatorPolicyCapability::CAN_EDIT);
 
     $id = $paste->getID();
+    $edit_uri = $this->getApplicationURI("edit/{$id}/");
+    $archive_uri = $this->getApplicationURI("archive/{$id}/");
+    $raw_uri = $this->getApplicationURI("raw/{$id}/");
 
-    $action_list = id(new PhabricatorActionListView())
+    $curtain->addAction(
-      ->setUser($viewer)
-      ->setObject($paste);
-
-    $action_list->addAction(
       id(new PhabricatorActionView())
         ->setName(pht('Edit Paste'))
         ->setIcon('fa-pencil')
         ->setDisabled(!$can_edit)
-          ->setHref($this->getApplicationURI("edit/{$id}/")));
+        ->setHref($edit_uri));
 
     if ($paste->isArchived()) {
-      $action_list->addAction(
+      $curtain->addAction(
         id(new PhabricatorActionView())
           ->setName(pht('Activate Paste'))
           ->setIcon('fa-check')
           ->setDisabled(!$can_edit)
           ->setWorkflow($can_edit)
-            ->setHref($this->getApplicationURI("archive/{$id}/")));
+          ->setHref($archive_uri));
     } else {
-      $action_list->addAction(
+      $curtain->addAction(
         id(new PhabricatorActionView())
           ->setName(pht('Archive Paste'))
           ->setIcon('fa-ban')
           ->setDisabled(!$can_edit)
           ->setWorkflow($can_edit)
-            ->setHref($this->getApplicationURI("archive/{$id}/")));
+          ->setHref($archive_uri));
     }
 
-    $action_list->addAction(
+    $curtain->addAction(
       id(new PhabricatorActionView())
         ->setName(pht('View Raw File'))
         ->setIcon('fa-file-text-o')
-          ->setHref($this->getApplicationURI("raw/{$id}/")));
+        ->setHref($raw_uri));
 
-    return $action_list;
+    return $curtain;
   }
 
 
@@ -191,32 +183,4 @@ final class PhabricatorPasteViewController extends PhabricatorPasteController {
       ->setContent($content);
   }
 
-  private function buildPropertyView(
-    PhabricatorPaste $paste,
-    array $child_phids) {
-    $viewer = $this->getViewer();
-
-    $properties = id(new PHUIPropertyListView())
-      ->setUser($viewer)
-      ->setObject($paste);
-
-    if ($paste->getParentPHID()) {
-      $properties->addProperty(
-        pht('Forked From'),
-        $viewer->renderHandle($paste->getParentPHID()));
-    }
-
-    if ($child_phids) {
-      $properties->addProperty(
-        pht('Forks'),
-        $viewer->renderHandleList($child_phids));
-    }
-
-    $descriptions = PhabricatorPolicyQuery::renderPolicyDescriptions(
-      $viewer,
-      $paste);
-
-    return $properties;
-  }
-
 }

src/applications/project/engineextension/PhabricatorProjectsCurtainExtension.php

@@ -0,0 +1,91 @@
+<?php
+
+final class PhabricatorProjectsCurtainExtension
+  extends PHUICurtainExtension {
+
+  const EXTENSIONKEY = 'projects.projects';
+
+  public function shouldEnableForObject($object) {
+    return ($object instanceof PhabricatorProjectInterface);
+  }
+
+  public function getExtensionApplication() {
+    return new PhabricatorProjectApplication();
+  }
+
+  public function buildCurtainPanel($object) {
+    $viewer = $this->getViewer();
+
+    $project_phids = PhabricatorEdgeQuery::loadDestinationPHIDs(
+      $object->getPHID(),
+      PhabricatorProjectObjectHasProjectEdgeType::EDGECONST);
+
+    $has_projects = (bool)$project_phids;
+    $project_phids = array_reverse($project_phids);
+    $handles = $viewer->loadHandles($project_phids);
+
+    // If this object can appear on boards, build the workboard annotations.
+    // Some day, this might be a generic interface. For now, only tasks can
+    // appear on boards.
+    $can_appear_on_boards = ($object instanceof ManiphestTask);
+
+    $annotations = array();
+    if ($has_projects && $can_appear_on_boards) {
+      $engine = id(new PhabricatorBoardLayoutEngine())
+        ->setViewer($viewer)
+        ->setBoardPHIDs($project_phids)
+        ->setObjectPHIDs(array($object->getPHID()))
+        ->executeLayout();
+
+      // TDOO: Generalize this UI and move it out of Maniphest.
+      require_celerity_resource('maniphest-task-summary-css');
+
+      foreach ($project_phids as $project_phid) {
+        $handle = $handles[$project_phid];
+
+        $columns = $engine->getObjectColumns(
+          $project_phid,
+          $object->getPHID());
+
+        $annotation = array();
+        foreach ($columns as $column) {
+          $project_id = $column->getProject()->getID();
+
+          $column_name = pht('(%s)', $column->getDisplayName());
+          $column_link = phutil_tag(
+            'a',
+            array(
+              'href' => "/project/board/{$project_id}/",
+              'class' => 'maniphest-board-link',
+            ),
+            $column_name);
+
+          $annotation[] = $column_link;
+        }
+
+        if ($annotation) {
+          $annotations[$project_phid] = array(
+            ' ',
+            phutil_implode_html(', ', $annotation),
+          );
+        }
+      }
+
+    }
+
+    if ($has_projects) {
+      $list = id(new PHUIHandleTagListView())
+        ->setHandles($handles)
+        ->setAnnotations($annotations)
+        ->setShowHovercards(true);
+    } else {
+      $list = phutil_tag('em', array(), pht('None'));
+    }
+
+    return $this->newPanel()
+      ->setHeaderText(pht('Projects'))
+      ->setOrder(10000)
+      ->appendChild($list);
+  }
+
+}

src/applications/subscriptions/engineextension/PhabricatorSubscriptionsCurtainExtension.php

@@ -0,0 +1,39 @@
+<?php
+
+final class PhabricatorSubscriptionsCurtainExtension
+  extends PHUICurtainExtension {
+
+  const EXTENSIONKEY = 'subscriptions.subscribers';
+
+  public function shouldEnableForObject($object) {
+    return ($object instanceof PhabricatorSubscribableInterface);
+  }
+
+  public function getExtensionApplication() {
+    return new PhabricatorSubscriptionsApplication();
+  }
+
+  public function buildCurtainPanel($object) {
+    $viewer = $this->getViewer();
+    $object_phid = $object->getPHID();
+
+    $subscriber_phids = PhabricatorSubscribersQuery::loadSubscribersForPHID(
+      $object_phid);
+
+    $handles = $viewer->loadHandles($subscriber_phids);
+
+    // TODO: This class can't accept a HandleList yet.
+    $handles = iterator_to_array($handles);
+
+    $susbscribers_view = id(new SubscriptionListStringBuilder())
+      ->setObjectPHID($object_phid)
+      ->setHandles($handles)
+      ->buildPropertyString();
+
+    return $this->newPanel()
+      ->setHeaderText(pht('Subscribers'))
+      ->setOrder(20000)
+      ->appendChild($susbscribers_view);
+  }
+
+}

src/applications/tokens/engineextension/PhabricatorTokensCurtainExtension.php

@@ -0,0 +1,67 @@
+<?php
+
+final class PhabricatorTokensCurtainExtension
+  extends PHUICurtainExtension {
+
+  const EXTENSIONKEY = 'tokens.tokens';
+
+  public function shouldEnableForObject($object) {
+    return ($object instanceof PhabricatorTokenReceiverInterface);
+  }
+
+  public function getExtensionApplication() {
+    return new PhabricatorTokensApplication();
+  }
+
+  public function buildCurtainPanel($object) {
+    $viewer = $this->getViewer();
+
+    $tokens_given = id(new PhabricatorTokenGivenQuery())
+      ->setViewer($viewer)
+      ->withObjectPHIDs(array($object->getPHID()))
+      ->execute();
+    if (!$tokens_given) {
+      return null;
+    }
+
+    $author_phids = mpull($tokens_given, 'getAuthorPHID');
+    $handles = $viewer->loadHandles($author_phids);
+
+    Javelin::initBehavior('phabricator-tooltips');
+
+    $list = array();
+    foreach ($tokens_given as $token_given) {
+      $token = $token_given->getToken();
+
+      $aural = javelin_tag(
+        'span',
+        array(
+          'aural' => true,
+        ),
+        pht(
+          '"%s" token, awarded by %s.',
+          $token->getName(),
+          $handles[$token_given->getAuthorPHID()]->getName()));
+
+      $list[] = javelin_tag(
+        'span',
+        array(
+          'sigil' => 'has-tooltip',
+          'class' => 'token-icon',
+          'meta' => array(
+            'tip' => $handles[$token_given->getAuthorPHID()]->getName(),
+          ),
+        ),
+        array(
+          $aural,
+          $token->renderIcon(),
+        ));
+    }
+
+    return $this->newPanel()
+      ->setHeaderText(pht('Tokens'))
+      ->setOrder(30000)
+      ->appendChild($list);
+  }
+
+}

src/applications/tokens/query/PhabricatorTokenGivenQuery.php

@@ -58,10 +58,12 @@ final class PhabricatorTokenGivenQuery
   }
 
   protected function willFilterPage(array $results) {
+    $viewer = $this->getViewer();
+
     $object_phids = mpull($results, 'getObjectPHID');
 
     $objects = id(new PhabricatorObjectQuery())
-      ->setViewer($this->getViewer())
+      ->setViewer($viewer)
       ->withPHIDs($object_phids)
       ->execute();
     $objects = mpull($objects, null, 'getPHID');
@@ -80,6 +82,31 @@ final class PhabricatorTokenGivenQuery
       unset($results[$key]);
     }
 
+    if (!$results) {
+      return $results;
+    }
+
+    $token_phids = mpull($results, 'getTokenPHID');
+
+    $tokens = id(new PhabricatorTokenQuery())
+      ->setViewer($viewer)
+      ->withPHIDs($token_phids)
+      ->execute();
+    $tokens = mpull($tokens, null, 'getPHID');
+
+    foreach ($results as $key => $result) {
+      $token_phid = $result->getTokenPHID();
+
+      $token = idx($tokens, $token_phid);
+      if (!$token) {
+        $this->didRejectResult($result);
+        unset($results[$key]);
+        continue;
+      }
+
+      $result->attachToken($token);
+    }
+
     return $results;
   }
 

src/applications/tokens/storage/PhabricatorTokenGiven.php

@@ -8,6 +8,7 @@ final class PhabricatorTokenGiven extends PhabricatorTokenDAO
   protected $tokenPHID;
 
   private $object = self::ATTACHABLE;
+  private $token = self::ATTACHABLE;
 
   protected function getConfiguration() {
     return array(
@@ -35,6 +36,15 @@ final class PhabricatorTokenGiven extends PhabricatorTokenDAO
     return $this->assertAttached($this->object);
   }
 
+  public function attachToken(PhabricatorToken $token) {
+    $this->token = $token;
+    return $this;
+  }
+
+  public function getToken() {
+    return $this->assertAttached($this->token);
+  }
+
   public function getCapabilities() {
     return array(
       PhabricatorPolicyCapability::CAN_VIEW,

src/view/extension/PHUICurtainExtension.php

@@ -0,0 +1,124 @@
+<?php
+
+abstract class PHUICurtainExtension extends Phobject {
+
+  private $viewer;
+
+  public function setViewer(PhabricatorUser $viewer) {
+    $this->viewer = $viewer;
+    return $this;
+  }
+
+  public function getViewer() {
+    return $this->viewer;
+  }
+
+  abstract public function shouldEnableForObject($object);
+  abstract public function getExtensionApplication();
+
+  public function buildCurtainPanels($object) {
+    $panel = $this->buildCurtainPanel($object);
+
+    if ($panel !== null) {
+      return array($panel);
+    }
+
+    return array();
+  }
+
+  public function buildCurtainPanel($object) {
+    throw new PhutilMethodNotImplementedException();
+  }
+
+  final public function getExtensionKey() {
+    return $this->getPhobjectClassConstant('EXTENSIONKEY');
+  }
+
+  final public static function getAllExtensions() {
+    return id(new PhutilClassMapQuery())
+      ->setAncestorClass(__CLASS__)
+      ->setUniqueMethod('getExtensionKey')
+      ->execute();
+  }
+
+  protected function newPanel() {
+    return new PHUICurtainPanelView();
+  }
+
+  final public static function buildExtensionPanels(
+    PhabricatorUser $viewer,
+    $object) {
+
+    $extensions = self::getAllExtensions();
+    foreach ($extensions as $extension) {
+      $extension->setViewer($viewer);
+    }
+
+    foreach ($extensions as $key => $extension) {
+      $application = $extension->getExtensionApplication();
+      if (!($application instanceof PhabricatorApplication)) {
+        throw new Exception(
+          pht(
+            'Curtain extension ("%s", of class "%s") did not return an '.
+            'application from method "%s". This method must return an '.
+            'object of class "%s".',
+            $key,
+            get_class($extension),
+            'getExtensionApplication()',
+            'PhabricatorApplication'));
+      }
+
+      $has_application = PhabricatorApplication::isClassInstalledForViewer(
+        get_class($application),
+        $viewer);
+
+      if (!$has_application) {
+        unset($extensions[$key]);
+      }
+    }
+
+    foreach ($extensions as $key => $extension) {
+      if (!$extension->shouldEnableForObject($object)) {
+        unset($extensions[$key]);
+      }
+    }
+
+    $result = array();
+
+    foreach ($extensions as $key => $extension) {
+      $panels = $extension->buildCurtainPanels($object);
+      if (!is_array($panels)) {
+        throw new Exception(
+          pht(
+            'Curtain extension ("%s", of class "%s") did not return a list of '.
+            'curtain panels from method "%s". This method must return an '.
+            'array, and each value in the array must be a "%s" object.',
+            $key,
+            get_class($extension),
+            'buildCurtainPanels()',
+            'PHUICurtainPanelView'));
+      }
+
+      foreach ($panels as $panel_key => $panel) {
+        if (!($panel instanceof PHUICurtainPanelView)) {
+          throw new Exception(
+            pht(
+              'Curtain extension ("%s", of class "%s") returned a list of '.
+              'curtain panels from "%s" that contains an invalid value: '.
+              'a value (with key "%s") is not an object of class "%s". '.
+              'Each item in the returned array must be a panel.',
+              $key,
+              get_class($extension),
+              'buildCurtainPanels()',
+              $panel_key,
+              'PHUICurtainPanelView'));
+        }
+
+        $result[] = $panel;
+      }
+    }
+
+    return $result;
+  }
+
+}

src/view/layout/PHUICurtainPanelView.php

@@ -0,0 +1,63 @@
+<?php
+
+final class PHUICurtainPanelView extends AphrontTagView {
+
+  private $order = 0;
+  private $headerText;
+
+  public function setHeaderText($header_text) {
+    $this->headerText = $header_text;
+    return $this;
+  }
+
+  public function getHeaderText() {
+    return $this->headerText;
+  }
+
+  public function setOrder($order) {
+    $this->order = $order;
+    return $this;
+  }
+
+  public function getOrder() {
+    return $this->order;
+  }
+
+  public function getOrderVector() {
+    return id(new PhutilSortVector())
+      ->addInt($this->getOrder());
+  }
+
+  protected function getTagAttributes() {
+    return array(
+      'class' => 'phui-curtain-panel',
+    );
+  }
+
+  protected function getTagContent() {
+    $header = null;
+
+    $header_text = $this->getHeaderText();
+    if (strlen($header_text)) {
+      $header = phutil_tag(
+        'div',
+        array(
+          'class' => 'phui-curtain-panel-header',
+        ),
+        $header_text);
+    }
+
+    $body = phutil_tag(
+      'div',
+      array(
+        'class' => 'phui-curtain-panel-body',
+      ),
+      $this->renderChildren());
+
+    return array(
+      $header,
+      $body,
+    );
+  }
+
+}

src/view/layout/PHUICurtainView.php

@@ -0,0 +1,52 @@
+<?php
+
+final class PHUICurtainView extends AphrontTagView {
+
+  private $actionList;
+  private $panels = array();
+
+  public function addAction(PhabricatorActionView $action) {
+    $this->getActionList()->addAction($action);
+    return $this;
+  }
+
+  public function addPanel(PHUICurtainPanelView $curtain_panel) {
+    $this->panels[] = $curtain_panel;
+    return $this;
+  }
+
+  public function setActionList(PhabricatorActionListView $action_list) {
+    $this->actionList = $action_list;
+    return $this;
+  }
+
+  public function getActionList() {
+    return $this->actionList;
+  }
+
+  protected function canAppendChild() {
+    return false;
+  }
+
+  protected function getTagContent() {
+    $action_list = $this->actionList;
+
+    require_celerity_resource('phui-curtain-view-css');
+
+    $panels = $this->renderPanels();
+
+    return id(new PHUIObjectBoxView())
+      ->appendChild($action_list)
+      ->appendChild($panels)
+      ->addClass('phui-two-column-properties');
+  }
+
+  private function renderPanels() {
+    $panels = $this->panels;
+    $panels = msortv($panels, 'getOrderVector');
+
+    return $panels;
+  }
+
+
+}

src/view/phui/PHUITwoColumnView.php

@@ -11,6 +11,7 @@ final class PHUITwoColumnView extends AphrontTagView {
   private $propertySection = array();
   private $actionList;
   private $propertyList;
+  private $curtain;
 
   const DISPLAY_LEFT = 'phui-side-column-left';
   const DISPLAY_RIGHT = 'phui-side-column-right';
@@ -50,6 +51,15 @@ final class PHUITwoColumnView extends AphrontTagView {
     return $this;
   }
 
+  public function setCurtain(PHUICurtainView $curtain) {
+    $this->curtain = $curtain;
+    return $this;
+  }
+
+  public function getCurtain() {
+    return $this->curtain;
+  }
+
   public function setFluid($fluid) {
     $this->fluid = $fluid;
     return $this;
@@ -98,9 +108,17 @@ final class PHUITwoColumnView extends AphrontTagView {
 
     $header = null;
     if ($this->header) {
-      if ($this->actionList) {
+      $curtain = $this->getCurtain();
-        $this->header->setActionList($this->actionList);
+      if ($curtain) {
+        $action_list = $curtain->getActionList();
+      } else {
+        $action_list = $this->actionList;
       }
+
+      if ($action_list) {
+        $this->header->setActionList($action_list);
+      }
+
       $header = phutil_tag_div(
         'phui-two-column-header', $this->header);
     }
@@ -166,6 +184,8 @@ final class PHUITwoColumnView extends AphrontTagView {
         ->addClass('phui-two-column-properties');
     }
 
+    $curtain = $this->getCurtain();
+
     return phutil_tag(
       'div',
       array(
@@ -173,6 +193,7 @@ final class PHUITwoColumnView extends AphrontTagView {
       ),
       array(
         $properties,
+        $curtain,
         $this->sideColumn,
       ));
   }

webroot/rsrc/css/phui/phui-curtain-view.css

@@ -0,0 +1,22 @@
+/**
+ * @provides phui-curtain-view-css
+ */
+
+.phui-curtain-panel {
+  margin: 4px;
+  padding: 4px 0;
+}
+
+.device-desktop .phui-curtain-panel {
+  border-top: 1px solid {$lightblueborder};
+}
+
+.phui-curtain-panel-header {
+  padding: 4px 0 0;
+  color: {$bluetext};
+  font-weight: bold;
+}
+
+.phui-curtain-panel-body {
+  padding: 4px 0 0;
+}