Add fold tiddler toolbar button

Addressing this tweet:
https://twitter.com/s_stryjecki/status/629349768280604672

core/images/fold-button.tid

@@ -0,0 +1,9 @@
+title: $:/core/images/fold-button
+tags: $:/tags/Image
+
+<svg class="tc-image-fold tc-image-button" width="22pt" height="22pt" viewBox="0 0 128 128">
+    <g fill-rule="evenodd">
+        <rect x="0" y="0" width="128" height="16" rx="8"></rect>
+        <path d="M40,118 L40,62.0000511 C40,57.5797863 36.418278,54 32,54 C27.5907123,54 24,57.5817449 24,62.0000511 L24,125.999949 C24,130.409288 27.5817449,134 32.0000511,134 L95.9999489,134 C100.420214,134 104,130.418278 104,126 C104,121.590712 100.418255,118 95.9999489,118 L40,118 Z" id="Rectangle-432-Copy" transform="translate(64.000000, 94.000000) scale(1, -1) rotate(-45.000000) translate(-64.000000, -94.000000) "></path>
+    </g>
+</svg>

core/images/unfold-button.tid

@@ -0,0 +1,9 @@
+title: $:/core/images/unfold-button
+tags: $:/tags/Image
+
+<svg class="tc-image-unfold tc-image-button" width="22pt" height="22pt" viewBox="0 0 128 128">
+    <g fill-rule="evenodd">
+        <rect x="0" y="0" width="128" height="16" rx="8"></rect>
+        <path d="M40,73 L40,17.0000511 C40,12.5797863 36.418278,9 32,9 C27.5907123,9 24,12.5817449 24,17.0000511 L24,80.9999489 C24,85.4092877 27.5817449,89 32.0000511,89 L95.9999489,89 C100.420214,89 104,85.418278 104,81 C104,76.5907123 100.418255,73 95.9999489,73 L40,73 Z" transform="translate(64.000000, 49.000000) rotate(-45.000000) translate(-64.000000, -49.000000) "></path>
+    </g>
+</svg>

core/language/en-GB/Buttons.multids

@@ -30,6 +30,8 @@ ExportTiddler/Caption: export tiddler
 ExportTiddler/Hint: Export tiddler
 ExportTiddlers/Caption: export tiddlers
 ExportTiddlers/Hint: Export tiddlers
+Fold/Caption: fold/unfold tiddler
+Fold/Hint: Fold/unfold the body of this tiddler
 FullScreen/Caption: full-screen
 FullScreen/Hint: Enter or leave full-screen mode
 Help/Caption: help

core/modules/widgets/navigator.js

@@ -29,7 +29,8 @@ var NavigatorWidget = function(parseTreeNode,options) {
 		{type: "tm-close-other-tiddlers", handler: "handleCloseOtherTiddlersEvent"},
 		{type: "tm-new-tiddler", handler: "handleNewTiddlerEvent"},
 		{type: "tm-import-tiddlers", handler: "handleImportTiddlersEvent"},
-		{type: "tm-perform-import", handler: "handlePerformImportEvent"}
+		{type: "tm-perform-import", handler: "handlePerformImportEvent"},
+		{type: "tm-fold-tiddler", handler: "handleFoldTiddlerEvent"}
 	]);
 };
 
@@ -569,6 +570,15 @@ NavigatorWidget.prototype.handlePerformImportEvent = function(event) {
 	$tw.rootWidget.dispatchEvent({type: "tm-auto-save-wiki"});
 };
 
+NavigatorWidget.prototype.handleFoldTiddlerEvent = function(event) {
+	var self = this,
+		paramObject = event.paramObject || {};
+	if(paramObject.foldedState) {
+		var foldedState = this.wiki.getTiddlerText(paramObject.foldedState,"show") === "show" ? "hide" : "show";
+		this.wiki.setText(paramObject.foldedState,"text",null,foldedState);
+	}
+};
+
 exports.navigator = NavigatorWidget;
 
 })();

core/ui/PageTemplate/sidebar.tid

@@ -5,7 +5,7 @@ tags: $:/tags/PageTemplate
 
 <div class="tc-sidebar-header">
 
-<$reveal state="$:/state/sidebar" type="match" text="yes" default="yes" retain="yes">
+<$reveal state="$:/state/sidebar" type="match" text="yes" default="yes" retain="yes" animate="yes">
 
 <h1 class="tc-site-title">
 

core/ui/ViewTemplate/body.tid

@@ -1,8 +1,14 @@
 title: $:/core/ui/ViewTemplate/body
 tags: $:/tags/ViewTemplate
 
+\define folded-state()
+$:/state/folded/$(currentTiddler)$
+\end
+
 <div class="tc-tiddler-body">
 
+<$reveal type="nomatch" state=<<folded-state>> text="hide" retain="yes" animate="yes">
+
 <$list filter="[all[current]!has[plugin-type]!field:hide-body[yes]]">
 
 <$transclude>
@@ -13,4 +19,6 @@ tags: $:/tags/ViewTemplate
 
 </$list>
 
+</$reveal>
+
 </div>

core/ui/ViewTemplate/subtitle.tid

@@ -1,8 +1,14 @@
 title: $:/core/ui/ViewTemplate/subtitle
 tags: $:/tags/ViewTemplate
 
+\define folded-state()
+$:/state/folded/$(currentTiddler)$
+\end
+
+<$reveal type="nomatch" state=<<folded-state>> text="hide" tag="div" retain="yes" animate="yes">
 <div class="tc-subtitle">
 <$link to={{!!modifier}}>
 <$view field="modifier"/>
 </$link> <$view field="modified" format="relativedate"/>
 </div>
+</$reveal>

core/ui/ViewTemplate/tags.tid

@@ -1,4 +1,10 @@
 title: $:/core/ui/ViewTemplate/tags
 tags: $:/tags/ViewTemplate
 
+\define folded-state()
+$:/state/folded/$(currentTiddler)$
+\end
+
+<$reveal type="nomatch" state=<<folded-state>> text="hide" tag="div" retain="yes" animate="yes">
 <div class="tc-tags-wrapper"><$list filter="[all[current]tags[]sort[title]]" template="$:/core/ui/TagTemplate" storyview="pop"/></div>
+</$reveal>

core/ui/ViewToolbar/fold.tid

@@ -0,0 +1,23 @@
+title: $:/core/ui/Buttons/fold
+tags: $:/tags/ViewToolbar
+caption: {{$:/core/images/fold-button}} {{$:/language/Buttons/Fold/Caption}}
+description: {{$:/language/Buttons/Fold/Hint}}
+
+\define folded-state()
+$:/state/folded/$(currentTiddler)$
+\end
+
+<$button tooltip={{$:/language/Buttons/Fold/Hint}} aria-label={{$:/language/Buttons/Fold/Caption}} class=<<tv-config-toolbar-class>>>
+<$action-sendmessage $message="tm-fold-tiddler" $param=<<currentTiddler>> foldedState=<<folded-state>>/>
+<$list filter="[<tv-config-toolbar-icons>prefix[yes]]" variable="listItem">
+<$reveal type="nomatch" state=<<folded-state>> text="hide" default="show">
+{{$:/core/images/fold-button}}
+</$reveal>
+<$reveal type="match" state=<<folded-state>> text="hide" default="show">
+{{$:/core/images/unfold-button}}
+</$reveal>
+</$list>
+<$list filter="[<tv-config-toolbar-text>prefix[yes]]">
+<span class="tc-btn-text"><$text text={{$:/language/Buttons/Fold/Caption}}/></span>
+</$list>
+</$button>

core/wiki/tags/ViewToolbar.tid

@@ -1,2 +1,2 @@
 title: $:/tags/ViewToolbar
-list: [[$:/core/ui/Buttons/more-tiddler-actions]] [[$:/core/ui/Buttons/info]] [[$:/core/ui/Buttons/new-here]] [[$:/core/ui/Buttons/new-journal-here]] [[$:/core/ui/Buttons/clone]] [[$:/core/ui/Buttons/export-tiddler]] [[$:/core/ui/Buttons/edit]] [[$:/core/ui/Buttons/delete]] [[$:/core/ui/Buttons/permalink]] [[$:/core/ui/Buttons/permaview]] [[$:/core/ui/Buttons/open-window]] [[$:/core/ui/Buttons/close-others]] [[$:/core/ui/Buttons/close]]
+list: [[$:/core/ui/Buttons/fold]] [[$:/core/ui/Buttons/more-tiddler-actions]] [[$:/core/ui/Buttons/info]] [[$:/core/ui/Buttons/new-here]] [[$:/core/ui/Buttons/new-journal-here]] [[$:/core/ui/Buttons/clone]] [[$:/core/ui/Buttons/export-tiddler]] [[$:/core/ui/Buttons/edit]] [[$:/core/ui/Buttons/delete]] [[$:/core/ui/Buttons/permalink]] [[$:/core/ui/Buttons/permaview]] [[$:/core/ui/Buttons/open-window]] [[$:/core/ui/Buttons/close-others]] [[$:/core/ui/Buttons/close]]

themes/tiddlywiki/vanilla/base.tid

@@ -620,7 +620,7 @@ button.tc-untagged-label {
 	    z-index: 1000;
 	    background-color: <<colour page-background>>;
 	    width: 100%;
-	    max-height: 50%;
+	    max-height: 100%;
 		<<if-no-sidebar "
 		    width: auto;
 		    max-height: auto;