Index: resources/celerity/map.php
===================================================================
--- resources/celerity/map.php
+++ resources/celerity/map.php
@@ -7,7 +7,7 @@
 return array(
   'names' =>
   array(
-    'core.pkg.css' => '8c8b76a8',
+    'core.pkg.css' => '76aa3fcd',
     'core.pkg.js' => '8f7aa2c3',
     'darkconsole.pkg.js' => 'ca8671ce',
     'differential.pkg.css' => '6aef439e',
@@ -21,7 +21,7 @@
     'rsrc/css/aphront/aphront-notes.css' => '6acadd3f',
     'rsrc/css/aphront/context-bar.css' => '1c3b0529',
     'rsrc/css/aphront/dark-console.css' => '6378ef3d',
-    'rsrc/css/aphront/dialog-view.css' => 'dd9db96c',
+    'rsrc/css/aphront/dialog-view.css' => 'c01d24b4',
     'rsrc/css/aphront/error-view.css' => '16cd9949',
     'rsrc/css/aphront/lightbox-attachment.css' => '686f8885',
     'rsrc/css/aphront/list-filter-view.css' => 'ef989c67',
@@ -483,7 +483,7 @@
     'aphront-bars' => '231ac33c',
     'aphront-contextbar-view-css' => '1c3b0529',
     'aphront-dark-console-css' => '6378ef3d',
-    'aphront-dialog-view-css' => 'dd9db96c',
+    'aphront-dialog-view-css' => 'c01d24b4',
     'aphront-error-view-css' => '16cd9949',
     'aphront-list-filter-view-css' => 'ef989c67',
     'aphront-multi-column-view-css' => '12f65921',
Index: src/applications/differential/controller/DifferentialCommentSaveControllerPro.php
===================================================================
--- src/applications/differential/controller/DifferentialCommentSaveControllerPro.php
+++ src/applications/differential/controller/DifferentialCommentSaveControllerPro.php
@@ -94,7 +94,7 @@
         ->withPHIDs($inline_phids)
         ->execute();
     } else {
-      $inlines = null;
+      $inlines = array();
     }
 
     foreach ($inlines as $inline) {
Index: src/applications/differential/editor/DifferentialTransactionEditor.php
===================================================================
--- src/applications/differential/editor/DifferentialTransactionEditor.php
+++ src/applications/differential/editor/DifferentialTransactionEditor.php
@@ -82,6 +82,14 @@
             return ($object->getStatus() != $status_revision);
           case DifferentialAction::ACTION_REQUEST:
             return ($object->getStatus() != $status_review);
+          case DifferentialAction::ACTION_RESIGN:
+            $actor_phid = $this->getActor()->getPHID();
+            foreach ($object->getReviewerStatus() as $reviewer) {
+              if ($reviewer->getReviewerPHID() == $actor_phid) {
+                return true;
+              }
+            }
+            return false;
         }
     }
 
@@ -113,6 +121,9 @@
         $status_revision = ArcanistDifferentialRevisionStatus::NEEDS_REVISION;
 
         switch ($xaction->getNewValue()) {
+          case DifferentialAction::ACTION_RESIGN:
+            // TODO: Update review status?
+            break;
           case DifferentialAction::ACTION_ABANDON:
             $object->setStatus(ArcanistDifferentialRevisionStatus::ABANDONED);
             break;
@@ -150,6 +161,41 @@
     return parent::applyCustomInternalTransaction($object, $xaction);
   }
 
+  protected function expandTransaction(
+    PhabricatorLiskDAO $object,
+    PhabricatorApplicationTransaction $xaction) {
+
+    $results = parent::expandTransaction($object, $xaction);
+    switch ($xaction->getTransactionType()) {
+      case DifferentialTransaction::TYPE_ACTION:
+        switch ($xaction->getNewValue()) {
+          case DifferentialAction::ACTION_RESIGN:
+            // If the user is resigning, add a separate reviewer edit
+            // transaction which removes them as a reviewer.
+
+            $actor_phid = $this->getActor()->getPHID();
+            $type_edge = PhabricatorTransactions::TYPE_EDGE;
+            $edge_reviewer = PhabricatorEdgeConfig::TYPE_DREV_HAS_REVIEWER;
+
+            $results[] = id(new DifferentialTransaction())
+              ->setTransactionType($type_edge)
+              ->setMetadataValue('edge:type', $edge_reviewer)
+              ->setIgnoreOnNoEffect(true)
+              ->setNewValue(
+                array(
+                  '-' => array(
+                    $actor_phid => $actor_phid,
+                  ),
+                ));
+
+            break;
+        }
+      break;
+    }
+
+    return $results;
+  }
+
   protected function applyCustomExternalTransaction(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
@@ -221,6 +267,11 @@
     $status_closed = ArcanistDifferentialRevisionStatus::CLOSED;
 
     switch ($action) {
+      case DifferentialAction::ACTION_RESIGN:
+        // You can always resign from a revision if you're a reviewer. If you
+        // aren't, this is a no-op rather than invalid.
+        break;
+
       case DifferentialAction::ACTION_ABANDON:
         if (!$actor_is_author) {
           return pht(
Index: src/applications/differential/storage/DifferentialTransaction.php
===================================================================
--- src/applications/differential/storage/DifferentialTransaction.php
+++ src/applications/differential/storage/DifferentialTransaction.php
@@ -121,7 +121,8 @@
         switch ($this->getMetadataValue('edge:type')) {
           case PhabricatorEdgeConfig::TYPE_DREV_HAS_REVIEWER:
             return pht(
-              'Those reviewers are already reviewing this revision.');
+              'The reviewers you are trying to add are already reviewing '.
+              'this revision.');
         }
         break;
       case DifferentialTransaction::TYPE_ACTION:
@@ -142,6 +143,10 @@
             return pht('This revision already requires changes.');
           case DifferentialAction::ACTION_REQUEST:
             return pht('Review is already requested for this revision.');
+          case DifferentialAction::ACTION_RESIGN:
+            return pht(
+              'You can not resign from this revision because you are not '.
+              'a reviewer.');
         }
         break;
     }
Index: src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php
===================================================================
--- src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php
+++ src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php
@@ -417,6 +417,7 @@
       $xactions[] = $mention_xaction;
     }
 
+    $xactions = $this->expandTransactions($object, $xactions);
     $xactions = $this->combineTransactions($xactions);
 
     foreach ($xactions as $xaction) {
@@ -853,6 +854,30 @@
     return null;
   }
 
+  /**
+   * Optionally expand transactions which imply other effects. For example,
+   * resigning from a revision in Differential implies removing yourself as
+   * a reviewer.
+   */
+  private function expandTransactions(
+    PhabricatorLiskDAO $object,
+    array $xactions) {
+
+    $results = array();
+    foreach ($xactions as $xaction) {
+      foreach ($this->expandTransaction($object, $xaction) as $expanded) {
+        $results[] = $expanded;
+      }
+    }
+
+    return $results;
+  }
+
+  protected function expandTransaction(
+    PhabricatorLiskDAO $object,
+    PhabricatorApplicationTransaction $xaction) {
+    return array($xaction);
+  }
 
   /**
    * Attempt to combine similar transactions into a smaller number of total
@@ -912,6 +937,12 @@
     }
     $u->setNewValue($result);
 
+    // When combining an "ignore" transaction with a normal transaction, make
+    // sure we don't propagate the "ignore" flag.
+    if (!$v->getIgnoreOnNoEffect()) {
+      $u->setIgnoreOnNoEffect(false);
+    }
+
     return $u;
   }
 
@@ -1128,6 +1159,8 @@
         if ($xaction->getTransactionType() != $type_comment) {
           $any_effect = true;
         }
+      } else if ($xaction->getIgnoreOnNoEffect()) {
+        unset($xactions[$key]);
       } else {
         $no_effect[$key] = $xaction;
       }
Index: src/applications/transactions/response/PhabricatorApplicationTransactionNoEffectResponse.php
===================================================================
--- src/applications/transactions/response/PhabricatorApplicationTransactionNoEffectResponse.php
+++ src/applications/transactions/response/PhabricatorApplicationTransactionNoEffectResponse.php
@@ -32,22 +32,28 @@
     $only_empty_comment = (count($xactions) == 1) &&
       (head($xactions)->getTransactionType() == $type_comment);
 
+    $count = new PhutilNumber(count($xactions));
+
     if ($ex->hasAnyEffect()) {
-      $title = pht('%d Action(s) With No Effect', count($xactions));
+      $title = pht('%d Action(s) With No Effect', $count);
+      $head = pht('Some of your %d action(s) have no effect:', $count);
       $tail = pht('Apply remaining actions?');
-      $continue = pht('Apply Other Actions');
+      $continue = pht('Apply Remaining Actions');
     } else if ($ex->hasComment()) {
       $title = pht('Post as Comment');
+      $head = pht('The %d action(s) you are taking have no effect:', $count);
       $tail = pht('Do you want to post your comment anyway?');
       $continue = pht('Post Comment');
     } else if ($only_empty_comment) {
       // Special case this since it's common and we can give the user a nicer
       // dialog than "Action Has No Effect".
       $title = pht('Empty Comment');
+      $head = null;
       $tail = null;
       $continue = null;
     } else {
-      $title = pht('%d Action(s) Have No Effect', count($xactions));
+      $title = pht('%d Action(s) Have No Effect', $count);
+      $head = pht('The %d action(s) you are taking have no effect:', $count);
       $tail = null;
       $continue = null;
     }
@@ -56,10 +62,17 @@
       ->setUser($request->getUser())
       ->setTitle($title);
 
+    $dialog->appendChild($head);
+
+    $list = array();
     foreach ($xactions as $xaction) {
-      $dialog->appendChild(
-        phutil_tag('p', array(), $xaction->getNoEffectDescription()));
+      $list[] = phutil_tag(
+        'li',
+        array(),
+        $xaction->getNoEffectDescription());
     }
+
+    $dialog->appendChild(phutil_tag('ul', array(), $list));
     $dialog->appendChild($tail);
 
     if ($continue) {
Index: src/applications/transactions/storage/PhabricatorApplicationTransaction.php
===================================================================
--- src/applications/transactions/storage/PhabricatorApplicationTransaction.php
+++ src/applications/transactions/storage/PhabricatorApplicationTransaction.php
@@ -31,6 +31,24 @@
   private $viewer = self::ATTACHABLE;
   private $object = self::ATTACHABLE;
 
+  private $ignoreOnNoEffect;
+
+
+  /**
+   * Flag this transaction as a pure side-effect which should be ignored when
+   * applying transactions if it has no effect, even if transaction application
+   * would normally fail. This both provides users with better error messages
+   * and allows transactions to perform optional side effects.
+   */
+  public function setIgnoreOnNoEffect($ignore) {
+    $this->ignoreOnNoEffect = $ignore;
+    return $this;
+  }
+
+  public function getIgnoreOnNoEffect() {
+    return $this->ignoreOnNoEffect;
+  }
+
   abstract public function getApplicationTransactionType();
 
   private function getApplicationObjectTypeName() {
Index: src/infrastructure/internationalization/translation/PhabricatorBaseEnglishTranslation.php
===================================================================
--- src/infrastructure/internationalization/translation/PhabricatorBaseEnglishTranslation.php
+++ src/infrastructure/internationalization/translation/PhabricatorBaseEnglishTranslation.php
@@ -215,6 +215,26 @@
         'Actions With No Effect',
       ),
 
+      'Some of your %d action(s) have no effect:' => array(
+        'One of your actions has no effect:',
+        'Some of your actions have no effect:',
+      ),
+
+      'Apply remaining %d action(s)?' => array(
+        'Apply remaining action?',
+        'Apply remaining actions?',
+      ),
+
+      'Apply %d Other Action(s)' => array(
+        'Apply Remaining Action',
+        'Apply Remaining Actions',
+      ),
+
+      'The %d action(s) you are taking have no effect:' => array(
+        'The action you are taking has no effect:',
+        'The actions you are taking have no effect:',
+      ),
+
       '%s edited post(s), added %d: %s; removed %d: %s.' =>
         '%s edited posts, added: %3$s; removed: %5$s',
 
Index: webroot/rsrc/css/aphront/dialog-view.css
===================================================================
--- webroot/rsrc/css/aphront/dialog-view.css
+++ webroot/rsrc/css/aphront/dialog-view.css
@@ -112,7 +112,7 @@
   width: 50%;
 }
 
-.aphront-access-dialog ul {
+.aphront-dialog-view ul {
   margin: 12px 24px;
   list-style: circle;
 }