diff --git a/editions/tw5.com/tiddlers/mechanisms/PopupMechanism.tid b/editions/tw5.com/tiddlers/mechanisms/PopupMechanism.tid
index a8cc56710..60566a329 100644
--- a/editions/tw5.com/tiddlers/mechanisms/PopupMechanism.tid
+++ b/editions/tw5.com/tiddlers/mechanisms/PopupMechanism.tid
@@ -1,13 +1,14 @@
 created: 20131212175656755
-modified: 20131212180213909
+modified: 20151223222712715
 tags: Mechanisms
 title: PopupMechanism
 type: text/vnd.tiddlywiki
 
 The popup mechanism allows blocks of content to be selectively displayed and positioned with respect to an anchor. It has several parts:
 
-* StateTiddlers to record whether a popup is currently displayed or not
+* [[StateTiddlers|StateMechanism]] to record whether a popup is currently displayed or not
 * The RevealWidget to selectively display the popup content
+** For "sticky" popups — those that don't close when clicking inside one — set the ''class'' attribute to `tc-popup-keep`
 * The ButtonWidget to trigger the display of the popup by setting the state tiddler appropriately
 
 
diff --git a/editions/tw5.com/tiddlers/widgets/RevealWidget.tid b/editions/tw5.com/tiddlers/widgets/RevealWidget.tid
index def34c3f4..18e1f6490 100644
--- a/editions/tw5.com/tiddlers/widgets/RevealWidget.tid
+++ b/editions/tw5.com/tiddlers/widgets/RevealWidget.tid
@@ -1,9 +1,9 @@
+caption: reveal
 created: 20131024141900000
-modified: 20150518163239603
+modified: 20151223222838652
 tags: Widgets
 title: RevealWidget
 type: text/vnd.tiddlywiki
-caption: reveal
 
 ! Introduction
 
@@ -22,7 +22,7 @@ The content of the `<$reveal>` widget is displayed according to the rules given
 |tag |Overrides the default HTML element tag (`<div>` in block mode or `<span>` in inline mode) |
 |type |The type of matching performed: ''match'', ''nomatch'' or ''popup'' |
 |text |The text to match when the type is ''match'' and ''nomatch'' |
-|class |An optional CSS class name to be assigned to the HTML element|
+|class |An optional CSS class name to be assigned to the HTML element<br/>&raquo; Set to `tc-popup-keep` to make a popup "sticky", so it won't close when you click inside of it|
 |style |An optional CSS style attribute to be assigned to the HTML element |
 |position |The position used for the popup when the type is ''popup''. Can be ''left'', ''above'', ''aboveright'', ''right'', ''belowleft'' or ''below'' |
 |default |Default value to use when the state tiddler is missing |