Add a "close plugin library" button (#2072)

* provides a "close plugin library" button

* starting from #1718 by @inmysocks
* possibly fixes all of #1718, #1597,  and #2067

* corrected code comment

* add back title

No idea why I overlooked this beforehand.

Next time I will not suggest such changes that have little to do with
the PR, but rather just comment the code.

* ah, sorry, "fixed" wrong spot

now

```
<$action-sendmessage $message="tm-load-plugin-from-library"
url={{!!url}} title={{$(assetInfo)$!!original-title}}/>
```

...should be back at the right spot.

* mhhh... still fixing the mess

load, unload, puh... let's see if I got it now

* added unloadIFrame and minor syntax fixes

core/language/en-GB/ControlPanel.multids

@@ -74,6 +74,7 @@ Plugins/NoInfoFound/Hint: No ''"<$text text=<<currentTab>>/>"'' found
 Plugins/NoInformation/Hint: No information provided
 Plugins/NotInstalled/Hint: This plugin is not currently installed
 Plugins/OpenPluginLibrary: open plugin library
+Plugins/ClosePluginLibrary: close plugin library
 Plugins/Plugins/Caption: Plugins
 Plugins/Plugins/Hint: Plugins
 Plugins/Reinstall/Caption: reinstall

core/modules/startup/browser-messaging.js

@@ -29,16 +29,17 @@ function loadIFrame(url,callback) {
 		callback(null,iframeInfo);
 	} else {
 		// Create the iframe and save it in the list
-		var iframe = document.createElement("iframe"),
-			iframeInfo = {
-				url: url,
-				status: "loading",
-				domNode: iframe
-			};
+		var iframe = document.createElement("iframe");
+		iframeInfo = {
+			url: url,
+			status: "loading",
+			domNode: iframe
+		};
 		$tw.browserMessaging.iframeInfoMap[url] = iframeInfo;
 		saveIFrameInfoTiddler(iframeInfo);
 		// Add the iframe to the DOM and hide it
 		iframe.style.display = "none";
+		iframe.setAttribute("library","true");
 		document.body.appendChild(iframe);
 		// Set up onload
 		iframe.onload = function() {
@@ -57,6 +58,18 @@ function loadIFrame(url,callback) {
 	}
 }
 
+/*
+Unload library iframe for given url
+*/
+function unloadIFrame(url){
+	$tw.utils.each(document.getElementsByTagName('iframe'), function(iframe) {
+		if(iframe.getAttribute("library") === "true" &&
+		  iframe.getAttribute("src") === url) {
+			iframe.parentNode.removeChild(iframe);
+		}
+	});
+}
+
 function saveIFrameInfoTiddler(iframeInfo) {
 	$tw.wiki.addTiddler(new $tw.Tiddler($tw.wiki.getCreationFields(),{
 		title: "$:/temp/ServerConnection/" + iframeInfo.url,
@@ -93,6 +106,21 @@ exports.startup = function() {
 			});
 		}
 	});
+	// Listen for widget messages to control unloading the plugin library
+	$tw.rootWidget.addEventListener("tm-unload-plugin-library",function(event) {
+		var paramObject = event.paramObject || {},
+			url = paramObject.url;
+		$tw.browserMessaging.iframeInfoMap[url] = undefined;
+		if(url) {
+			unloadIFrame(url);
+			$tw.utils.each(
+				$tw.wiki.filterTiddlers("[[$:/temp/ServerConnection/" + url + "]] [prefix[$:/temp/RemoteAssetInfo/" + url + "/]]"),
+				function(title) {
+					$tw.wiki.deleteTiddler(title);
+				}
+			);
+		}
+	});
 	$tw.rootWidget.addEventListener("tm-load-plugin-from-library",function(event) {
 		var paramObject = event.paramObject || {},
 			url = paramObject.url,

core/ui/ControlPanel/Modals/AddPlugins.tid

@@ -90,6 +90,16 @@ $:/state/add-plugin-info/$(connectionTiddler)$/$(assetInfo)$
 </$list>
 \end
 
+\define close-library-button()
+<$reveal type='nomatch' state='$:/temp/ServerConnection/$(PluginLibraryURL)$' text=''>
+<$button class='tc-btn-big-green'>
+<$action-sendmessage $message="tm-unload-plugin-library" url={{!!url}}/>
+{{$:/core/images/chevron-left}} {{$:/language/ControlPanel/Plugins/ClosePluginLibrary}}
+<$action-deletetiddler $filter="[prefix[$:/temp/ServerConnection/$(PluginLibraryURL)$]][prefix[$:/temp/RemoteAssetInfo/$(PluginLibraryURL)$]]"/>
+</$button>
+</$reveal>
+\end
+
 \define plugin-library-listing()
 <$list filter="[all[tiddlers+shadows]tag[$:/tags/PluginLibrary]]">
 <div class="tc-plugin-library">
@@ -100,6 +110,10 @@ $:/state/add-plugin-info/$(connectionTiddler)$/$(assetInfo)$
 
 <$transclude/>
 
+<$set name=PluginLibraryURL value={{!!url}}>
+<<close-library-button>>
+</$set>
+
 <<display-server-connection>>
 </div>
 </$list>