Add icon and message handler for print button

I’m inclined to think it’s not worth adding a corresponding page
control button because it’ll require a lot of tiddlers for the
translation etc.

core/images/print-button.tid

@@ -0,0 +1,12 @@
+title: $:/core/images/print-button
+tags: $:/tags/Image
+
+<svg class="tc-image-print-button tc-image-button" viewBox="0 0 128 128" width="22pt" height="22pt">
+    <g fill-rule="evenodd">
+        <path d="M112,71 L112,30.5 L111.96811,30.5 L111.96811,30.5 C111.932942,28.4998414 111.151676,26.510538 109.625176,24.9840387 L86.9982489,2.35711116 C85.3482153,0.707077645 83.1589869,-0.071534047 81,0.0201838424 L81,0 L23.9992458,0 C19.5808867,0 16,3.58213437 16,8.00092105 L16,71 L24,71 L24,8 L81,8 L81,22.4996539 C81,26.9216269 84.5818769,30.5 89.0003461,30.5 L104,30.5 L104,71 L112,71 Z"></path>
+        <rect x="32" y="36" width="64" height="8" rx="4"></rect>
+        <rect x="32" y="52" width="64" height="8" rx="4"></rect>
+        <rect x="32" y="20" width="40" height="8" rx="4"></rect>
+        <path d="M0,80.0054195 C0,71.1658704 7.15611005,64 16.0008841,64 L111.999116,64 C120.83616,64 128,71.1553215 128,80.0054195 L128,111.99458 C128,120.83413 120.84389,128 111.999116,128 L16.0008841,128 C7.16383982,128 0,120.844679 0,111.99458 L0,80.0054195 Z M104,96 C108.418278,96 112,92.418278 112,88 C112,83.581722 108.418278,80 104,80 C99.581722,80 96,83.581722 96,88 C96,92.418278 99.581722,96 104,96 Z"></path>
+    </g>
+</svg>

core/modules/startup/story.js

@@ -53,6 +53,10 @@ exports.startup = function() {
 		$tw.rootWidget.addEventListener("tm-browser-refresh",function(event) {
 			window.location.reload(true);
 		});
+		// Listen for the tm-print message
+		$tw.rootWidget.addEventListener("tm-print",function(event) {
+			window.print();
+		});
 		// Listen for the tm-home message
 		$tw.rootWidget.addEventListener("tm-home",function(event) {
 			window.location.hash = "";

editions/tw5.com/tiddlers/messages/WidgetMessage_ tm-print.tid

@@ -0,0 +1,10 @@
+created: 20161008085627406
+modified: 20161008085627406
+tags: Messages
+title: WidgetMessage: tm-print
+type: text/vnd.tiddlywiki
+caption: tm-print
+
+<<.from-version "5.1.14">> The `tm-print` message causes the browser to display the print dialog for the current page. It does not require any properties on the `event` object.
+
+The print message is usually generated with the ButtonWidget and is handled by the core.