Introduce a PageMacros tiddler containing a tabs macro

This is a hacky way of having macro definitions that behave as if they
are global to the wiki.

The new tabs macro itself is cool, though: neatly encapsulates most of
the gubbins around a tab control, and the rendering is quite easy to
style.

core/modules/startup.js

@@ -102,8 +102,8 @@ exports.startup = function() {
 		$tw.rootWidget.addEventListener("tw-clear-password",function(event) {
 			$tw.crypto.setPassword(null);
 		});
-		// Display the PageTemplate
-		var templateTitle = "$:/core/ui/PageTemplate",
+		// Display the PageMacros, which includes the PageTemplate
+		var templateTitle = "$:/core/ui/PageMacros",
 			parser = $tw.wiki.new_parseTiddler(templateTitle);
 		$tw.pageWidgetNode = $tw.wiki.makeWidget(parser,{document: document, parentWidget: $tw.rootWidget});
 		$tw.pageContainer = document.createElement("div");

core/ui/PageMacros.tid

@@ -0,0 +1,17 @@
+title: $:/core/ui/PageMacros
+
+\define tabs(tabsList,default,state:"$:/currentTab")
+<div class="tw-tab-buttons"><$list filter="$tabsList$" variable="currentTab"><$button set=<<qualify "$state$">> setTo=<<currentTab>> default="$default$" selectedClass="tw-tab-selected"><$macrocall $name="currentTab" $type="text/plain" $output="text/plain"/> </$button>
+</$list>
+</div>
+<div class="tw-tab-divider">
+</div>
+<div class="tw-tab-content">
+<$list filter="$tabsList$" variable="currentTab">
+<$reveal type="match" state=<<qualify "$state$">> text=<<currentTab>> default="$default$">
+<$transclude tiddler=<<currentTab>>/>
+</$reveal>
+</$list>
+</div>
+\end
+{{$:/core/ui/PageTemplate}}

core/wiki/moreSideBarTabSet.tid

@@ -1,3 +1,3 @@
-title: $:/state/moreSideBarTabSet-{$:/core/ui/MoreSideBar|$:/core/ui/MoreSideBar||}{$:/core/ui/SideBar|$:/core/ui/SideBar||}
+title: $:/state/moreSideBarTabSet-{$:/core/ui/MoreSideBar|$:/core/ui/MoreSideBar||}{$:/core/ui/SideBar|$:/core/ui/SideBar||}{$:/core/ui/PageTemplate|$:/core/ui/PageTemplate||}
 
 tagsTab

core/wiki/sideBarTabSet.tid

@@ -1,3 +1,3 @@
-title: $:/state/sideBarTabSet-{$:/core/ui/SideBar|$:/core/ui/SideBar||}
+title: $:/state/sideBarTabSet-{$:/core/ui/SideBar|$:/core/ui/SideBar||}{$:/core/ui/PageTemplate|$:/core/ui/PageTemplate||}
 
 openTab

editions/tw5.com/tiddlers/samples/TabsExample.tid

@@ -0,0 +1,8 @@
+title: TabsExample
+tags: samples
+
+Here is an example of the tabs macro:
+
+<<tabs "Docs WikiText Features RoadMap" "WikiText" 1>>
+
+<<tabs "[tag[tips]]" "GoogleChromeTips" 2>>