diff --git a/resources/celerity/map.php b/resources/celerity/map.php
--- a/resources/celerity/map.php
+++ b/resources/celerity/map.php
@@ -13,7 +13,7 @@
     'core.pkg.js' => '4c79d74f',
     'darkconsole.pkg.js' => '1f9a31bc',
     'differential.pkg.css' => '45951e9e',
-    'differential.pkg.js' => 'ae6460e0',
+    'differential.pkg.js' => '500a75c5',
     'diffusion.pkg.css' => 'a2d17c7d',
     'diffusion.pkg.js' => '6134c5a1',
     'favicon.ico' => '30672e08',
@@ -396,7 +396,7 @@
     'rsrc/js/application/dashboard/behavior-dashboard-query-panel-select.js' => '453c5375',
     'rsrc/js/application/dashboard/behavior-dashboard-tab-panel.js' => 'd4eecc63',
     'rsrc/js/application/diff/DiffChangeset.js' => '99abf4cd',
-    'rsrc/js/application/diff/DiffChangesetList.js' => '8f1cd52c',
+    'rsrc/js/application/diff/DiffChangesetList.js' => '3b77efdd',
     'rsrc/js/application/diff/DiffInline.js' => 'e83d28f3',
     'rsrc/js/application/diff/behavior-preview-link.js' => '051c7832',
     'rsrc/js/application/differential/behavior-comment-preview.js' => '51c5ad07',
@@ -775,7 +775,7 @@
     'phabricator-darkmessage' => 'c48cccdd',
     'phabricator-dashboard-css' => 'fe5b1869',
     'phabricator-diff-changeset' => '99abf4cd',
-    'phabricator-diff-changeset-list' => '8f1cd52c',
+    'phabricator-diff-changeset-list' => '3b77efdd',
     'phabricator-diff-inline' => 'e83d28f3',
     'phabricator-drag-and-drop-file-upload' => '58dea2fa',
     'phabricator-draggable-list' => 'bea6e7f4',
@@ -1137,6 +1137,10 @@
       'javelin-dom',
       'javelin-magical-init',
     ),
+    '3b77efdd' => array(
+      'javelin-install',
+      'phuix-button-view',
+    ),
     '3cb0b2fc' => array(
       'javelin-behavior',
       'javelin-dom',
@@ -1610,10 +1614,6 @@
     '8e1baf68' => array(
       'phui-button-css',
     ),
-    '8f1cd52c' => array(
-      'javelin-install',
-      'phuix-button-view',
-    ),
     '8f29b364' => array(
       'javelin-behavior',
       'javelin-stratcom',
diff --git a/src/applications/differential/view/DifferentialChangesetListView.php b/src/applications/differential/view/DifferentialChangesetListView.php
--- a/src/applications/differential/view/DifferentialChangesetListView.php
+++ b/src/applications/differential/view/DifferentialChangesetListView.php
@@ -301,6 +301,9 @@
 
         'Hide or show all inline comments.' =>
           pht('Hide or show all inline comments.'),
+
+        'Finish editing inline comments before changing display modes.' =>
+          pht('Finish editing inline comments before changing display modes.'),
       ),
     ));
 
diff --git a/webroot/rsrc/js/application/diff/DiffChangesetList.js b/webroot/rsrc/js/application/diff/DiffChangesetList.js
--- a/webroot/rsrc/js/application/diff/DiffChangesetList.js
+++ b/webroot/rsrc/js/application/diff/DiffChangesetList.js
@@ -465,7 +465,7 @@
       new JX.Notification()
         .setContent(message)
         .alterClassName('jx-notification-alert', true)
-        .setDuration(1000)
+        .setDuration(3000)
         .show();
     },
 
@@ -691,6 +691,7 @@
         'div',
         'differential-changeset');
 
+      var changeset_list = this;
       var changeset = this.getChangesetForNode(node);
 
       var menu = new JX.PHUIXDropdownMenu(button);
@@ -738,6 +739,22 @@
       var up_item = new JX.PHUIXActionView()
         .setHandler(function(e) {
           if (changeset.isLoaded()) {
+
+            // Don't let the user swap display modes if a comment is being
+            // edited, since they might lose their work. See PHI180.
+            var inlines = changeset.getInlines();
+            for (var ii = 0; ii < inlines.length; ii++) {
+              if (inlines[ii].isEditing()) {
+                changeset_list._warnUser(
+                  pht(
+                    'Finish editing inline comments before changing display ' +
+                    'modes.'));
+                e.prevent();
+                menu.close();
+                return;
+              }
+            }
+
             var renderer = changeset.getRenderer();
             if (renderer == '1up') {
               renderer = '2up';