Add support for story backdrop and frontdrop

Allows elements to be added above or below the story river

core/ui/PageTemplate/story.tid

@@ -3,6 +3,26 @@ tags: $:/tags/PageTemplate
 
 <section class="story-river">
 
-<$list filter="[list[$:/StoryList]]" history="$:/HistoryList" template="$:/core/ui/ViewTemplate" editTemplate="$:/core/ui/EditTemplate" storyview={{$:/view}} />
+<section class="story-backdrop">
+
+<$list filter="[all[shadows+tiddlers]tag[$:/tags/StoryBackdrop]!has[draft.of]]">
+
+<$transclude/>
+
+</$list>
+
+</section>
+
+<$list filter="[list[$:/StoryList]]" history="$:/HistoryList" template="$:/core/ui/ViewTemplate" editTemplate="$:/core/ui/EditTemplate" storyview={{$:/view}} />
+
+<section class="story-frontdrop">
+
+<$list filter="[all[shadows+tiddlers]tag[$:/tags/StoryFrontdrop]!has[draft.of]]">
+
+<$transclude/>
+
+</$list>
+
+</section>
 
 </section>

editions/tw5.com/tiddlers/concepts/SystemTags.tid

@@ -1,5 +1,5 @@
 created: 20130822080600000
-modified: 20131228161338857
+modified: 20140707161338857
 tags: concepts
 title: SystemTags
 type: text/vnd.tiddlywiki
@@ -17,6 +17,8 @@ System tags are used to give special behaviour to tiddlers:
 * [[$:/tags/EditToolbar]] for the edit mode tiddler toolbar
 * [[$:/tags/PageControls]] for the page control tools in the sidebar
 * [[$:/tags/PageTemplate]] for the main page elements
+* [[$:/tags/StoryBackdrop]] for elements to be placed at the top of the story river
+* [[$:/tags/StoryFrontdrop]] for elements to be placed at the bottom of the story river
 * [[$:/tags/RawMarkup]] for raw markup to be included in the generated HTML file
 
 ! System tags in use