diff --git a/scripts/gh-book/app.coffee b/scripts/gh-book/app.coffee
index 8991827a..3aca9726 100644
--- a/scripts/gh-book/app.coffee
+++ b/scripts/gh-book/app.coffee
@@ -95,11 +95,6 @@ define [
     mediaTypes.add BinaryFile, {mediaType:'image/png'}
     mediaTypes.add BinaryFile, {mediaType:'image/jpeg'}
 
-    # set which media formats are allowed 
-    # at the toplevel of the content
-    for type in EpubContainer::accept
-      mediaTypes.type(type)::toplevel = true
-
     # Views use anchors with hrefs so catch the click and send it to Backbone
     $(document).on 'click', 'a:not([data-bypass]):not([href="#"])', (e) ->
       external = new RegExp('^((f|ht)tps?:)?//')
diff --git a/scripts/views/layouts/workspace/sidebar.coffee b/scripts/views/layouts/workspace/sidebar.coffee
index 8c370c40..8fe831fb 100644
--- a/scripts/views/layouts/workspace/sidebar.coffee
+++ b/scripts/views/layouts/workspace/sidebar.coffee
@@ -37,7 +37,12 @@ define [
         # This is the Picker/Roots Sidebar
         collection = new Backbone.FilteredCollection(null, {collection:collection})
         collection.setFilter (content)  -> return content.getChildren
-        @filteredMediaTypes.setFilter (type) -> return type.get('modelType')::toplevel
+        # TODO: Remove `topLevel` from all models
+        @filteredMediaTypes.setFilter (type) ->
+          # Filter the types to exclude Chapters and other non-loadable content.
+          # Written this way to support `gh-book` **and** `atc`; if something is loadable then it is creatable.
+          return type.get('modelType')::load
+
 
       # TODO: Make the collection a FilteredCollection that only shows @model.accepts
       @addContent.show(new AddView {context:model, collection:@filteredMediaTypes})
diff --git a/scripts/views/workspace/menu/add.coffee b/scripts/views/workspace/menu/add.coffee
index 9c338327..d356796c 100644
--- a/scripts/views/workspace/menu/add.coffee
+++ b/scripts/views/workspace/menu/add.coffee
@@ -36,8 +36,8 @@ define [
       # Only add Models to `allContent` if they can be saved.
       #
       # ToC Sections, for example, cannot be saved but do implement Saveable because OpfFile extends TocNode
-      # So we use `.id` instead.
-      if model.id
+      # So we use `.load` instead.
+      if model.load
         allContent.add(model)
 
       # Add the model to the context