MINOR Documentation for CMS tree and new SiteTree->getStatusFlags()

docs/en/howto/customize-cms-tree.md

@@ -0,0 +1,76 @@
+# How to customize the CMS tree #
+
+## Overview
+
+The tree is rendered through `[api:LeftAndMain->getSiteTreeFor()]`,
+which recursively collects all nodes based on various filtering criteria.
+The node strictly just has to implement the `[api:Hierarchy]` extension,
+but in the CMS usually is a `[api:SiteTree]` object.
+
+## Add status lozenges to tree nodes ##
+
+A tree node in CMS could be rendered with lot of extra information but a node title, such as a
+link that wraps around the node title, a node's id which is given as id attribute of the node
+<li> tag, a extra checkbox beside the tree title, tree icon class or extra <span>
+tags showing the node status, etc. SilverStripe tree node will be typically rendered into html
+code like this:
+
+	:::ss
+	...
+	<ul>
+		...
+		<li id="record-15" class="class-Page closed jstree-leaf jstree-unchecked" data-id="15">
+		<ins class="jstree-icon">&nbsp;</ins>
+			<a class="" title="Page type: Page" href="admin/page/edit/show/15">
+				<ins class="jstree-checkbox">&nbsp;</ins>
+				<ins class="jstree-icon">&nbsp;</ins>
+				<span class="text">
+					<span class="jstree-pageicon"></span>
+					<span class="item" title="Deleted">New Page</span>
+					<span class="badge deletedonlive">Deleted</span>
+				</span>
+			</a>
+		</li>
+		...
+	</ul>
+	...
+	
+By applying the proper style sheet, the snippet html above could produce the look of:
+![Page Node Screenshot](../_images/tree_node.png "Page Node")
+
+SiteTree is a `[api:DataObject]` which is versioned by `[api:Versioned]` extension. 
+Each node can optionally have publication status flags, e.g. "Removed from draft".
+Each flag has a unique identifier, which is also used as a CSS class for easier styling.
+
+Developers can easily add a new flag, delete or alter an existing flag on how it is looked
+or changing the flag label. The customization of these lozenges could be done either through
+inherited subclass or `[api:DataExtension]`. It is just really about how we change the return
+value of function `SiteTree->getTreeTitle()` by two easily extendable methods
+`SiteTree->getStatusClass()` and `SiteTree->getStatusFlags()`.
+
+Note: Though the flag is not necessarily tie to its status of __publication__ and it could
+be used for flagging anything you like, we should keep this lozenge to show version-related
+status, while let `SiteTree->CMSTreeClasses()` to deal with other customised classes, which
+will be used for the class attribute of &lt;li&gt; tag of the tree node.
+
+### Add new flag ###
+__Example: using a subclass__
+
+	:::php
+	class Page extends SiteTree {
+		function getScheduledToPublish(){
+			// return either true or false
+		}
+
+		function getStatusFlags(){
+			$flags = parent::getStatusFlags();
+			$flags['scheduledtopublish'] = "Scheduled To Publish";
+			return $flags;
+		}
+	}
+
+The above subclass of `[api:SiteTree]` will add a new flag for indicating its
+__'Scheduled To Publish'__ status. The look of the page node will be changed
+from ![Normal Page Node](../_images/page_node_normal.png") to ![Scheduled Page Node](../_images/page_node_scheduled.png). The getStatusFlags has an `updateStatusFlags()`
+extension point, so the flags can be modified through `DataExtension` rather than
+inheritance as well. Deleting existing flags works by simply unsetting the array key.

docs/en/howto/index.md

@@ -11,6 +11,7 @@ the language and functions which are used in the guides.
 * [Grouping DataObjectSets](grouping-dataobjectsets). Group results in a [api:DataObjectSet] to create sub sections.
 * [PHPUnit Configuration](phpunit-configuration). How to setup your testing environment with PHPUnit
 * [Extend the CMS Interface](extend-cms-interface). 
+* [How to customize CMS Tree](customize-cms-tree).
 
 ## Feedback
 

docs/en/reference/cms-architecture.md

@@ -259,5 +259,6 @@ Note: You can see any additional HTTP headers through the web developer tools in
 ## Related
 
  * [Howto: Extend the CMS Interface](../howto/extend-cms-interface)
+ * [Howto: Customize the CMS tree](../howto/customize-cms-tree)
  * [Reference: ModelAdmin](../reference/modeladmin)
  * [Topics: Rich Text Editing](../topics/rich-text-editing)