Update modal handling to allow variables to be passed

@felixhayashi I’m afraid I haven’t used your pull request as there were
a few details that I wanted to do differently. The main change is that
these changes allow both a param string and hashmap to be specified.

core/modules/startup/rootwidget.js

@@ -23,7 +23,7 @@ exports.startup = function() {
 	// Install the modal message mechanism
 	$tw.modal = new $tw.utils.Modal($tw.wiki);
 	$tw.rootWidget.addEventListener("tm-modal",function(event) {
-		$tw.modal.display(event.param);
+		$tw.modal.display(event.param,{variables: event.paramObject});
 	});
 	// Install the notification  mechanism
 	$tw.notifier = new $tw.utils.Notifier($tw.wiki);

core/modules/utils/dom/modal.js

@@ -35,6 +35,8 @@ Modal.prototype.display = function(title,options) {
 	if(!tiddler) {
 		return;
 	}
+	// Create the variables
+	var variables = $tw.utils.extend({currentTiddler: title},options.variables);
 	// Create the wrapper divs
 	var wrapper = document.createElement("div"),
 		modalBackdrop = document.createElement("div"),
@@ -76,7 +78,8 @@ Modal.prototype.display = function(title,options) {
 					value: title
 		}}}],
 		parentWidget: $tw.rootWidget,
-		document: document
+		document: document,
+		variables: variables
 	});
 	headerWidgetNode.render(headerTitle,null);
 	this.wiki.addEventListener("change",function(changes) {
@@ -85,7 +88,8 @@ Modal.prototype.display = function(title,options) {
 	// Render the body of the message
 	var bodyWidgetNode = this.wiki.makeTranscludeWidget(title,{
 		parentWidget: $tw.rootWidget,
-		document: document
+		document: document,
+		variables: variables
 	});
 	bodyWidgetNode.render(modalBody,null);
 	this.wiki.addEventListener("change",function(changes) {
@@ -125,7 +129,8 @@ Modal.prototype.display = function(title,options) {
 			}}}
 		]}],
 		parentWidget: $tw.rootWidget,
-		document: document
+		document: document,
+		variables: variables
 	});
 	footerWidgetNode.render(modalFooterButtons,null);
 	this.wiki.addEventListener("change",function(changes) {

editions/prerelease/tiddlers/SampleModal.tid

@@ -0,0 +1,12 @@
+created: 20140912145537860
+footer: <$button message="tm-close-tiddler">Close</$button>
+modified: 20140912145537861
+subtitle: This is a modal created especially for <<yourName>>
+title: SampleModal
+type: text/vnd.tiddlywiki
+
+! Hello, <<yourName>>
+
+This is an example modal containing the following message:
+
+<<yourMessage>>

editions/prerelease/tiddlers/WidgetMessage_ tm-modal.tid

@@ -0,0 +1,32 @@
+created: 20140811112133701
+modified: 20141107142803042
+tags: Messages
+title: WidgetMessage: tm-modal
+type: text/vnd.tiddlywiki
+caption: tm-modal
+
+The modal message displays a specified tiddler in a modal overlay that dims the main page. It requires the following properties on the `event` object:
+
+|!Name |!Description |
+|param |Title of the tiddler to be displayed |
+|paramObject |Hashmap of variables to be provided to the modal |
+
+The "currentTiddler" variable is set to the title of the modal tiddler, but can be overridden by specifying a different value in `paramObject`.
+
+The modal message is usually generated with the ButtonWidget. The modal message is handled by the TiddlyWiki core.
+
+! Example
+
+Here is an example of displaying a modal and passing parameters to it:
+
+<$macrocall $name='wikitext-example-without-html'
+src='Your name: <$edit-text tiddler="$:/temp/yourName" tag="input" default="Your name"/>
+
+Your message:
+<$edit-text tiddler="$:/temp/yourMessage" default="Your message"/>
+
+<$button>
+<$action-sendmessage $message="tm-modal" $param="SampleModal" yourName={{$:/temp/yourName}} yourMessage={{$:/temp/yourMessage}}/>
+Click me!
+</$button>'/>
+