Allow plugins to add entire screens to Gerrit

Add an extension screen which contains a hook that can be used by
GWT and JS plugins to integrate complete screens into the Gerrit UI.

Change-Id: I48a92ea49c4384db034177b04b2e7f0bea6a87b2

Documentation/dev-plugins.txt

@@ -1498,6 +1498,48 @@ In order to be able to do REST calls the GWT module must inherit
 <inherits name="com.google.gwt.json.JSON"/>
 ----
 
+== Add Screen
+A GWT plugin can add a menu item that opens a screen that is
+implemented by the plugin. This way plugin screens can be fully
+integrated into the Gerrit UI.
+
+Example menu item:
+[source,java]
+----
+public class MyMenu implements TopMenu {
+  private final List<MenuEntry> menuEntries;
+
+  @Inject
+  public MyMenu(@PluginName String name) {
+    menuEntries = Lists.newArrayList();
+    menuEntries.add(new MenuEntry("My Menu", Collections.singletonList(
+      new MenuItem("My Screen", "#/x/" + name + "/my-screen", ""))));
+  }
+
+  @Override
+  public List<MenuEntry> getEntries() {
+    return menuEntries;
+  }
+}
+----
+
+Example screen:
+[source,java]
+----
+public class MyPlugin extends PluginEntryPoint {
+  @Override
+  public void onPluginLoad() {
+    Plugin.get().screen("my-screen", new Screen.EntryPoint() {
+      @Override
+      public void onLoad(Screen screen) {
+        screen.add(new InlineLabel("My Screen");
+        screen.show();
+      }
+    });
+  }
+}
+----
+
 [[http]]
 == HTTP Servlets
 

Documentation/js-api.txt

@@ -139,8 +139,8 @@ Gerrit.on(event, callback);
 
 Supported events:
 
-* `history`: Invoked when the view is changed to a new page within the
+* `history`: Invoked when the view is changed to a new screen within
-  Gerrit web application.  The token after "#" is passed as the
+  the Gerrit web application.  The token after "#" is passed as the
   argument to the callback function, for example "/c/42/" while
   showing change 42.
 
@@ -164,7 +164,7 @@ on a button associated with a server side `UiAction`.
 .Signature
 [source,javascript]
 ----
-Gerrit.onAction(type, view_name, callback);
+self.onAction(type, view_name, callback);
 ----
 
 * type: `'change'`, `'revision'` or `'project'`, indicating which type
@@ -177,6 +177,27 @@ Gerrit.onAction(type, view_name, callback);
 * callback: JavaScript function to invoke when the user clicks. The
   function will be passed a link:#ActionContext[action context].
 
+[[self_screen]]
+=== self.screen()
+Register a JavaScript callback to be invoked when the user navigates
+to an extension screen provided by the plugin. Extension screens are
+usually linked from the link:dev-plugins.html#top-menu-extensions[top menu].
+The callback can populate the DOM with the screen's contents.
+
+.Signature
+[source,javascript]
+----
+self.screen(pattern, callback);
+----
+
+* pattern: URL token pattern to identify the screen. Argument can be
+  either a string (`'index'`) or a RegExp object (`/list\/(.*)/`).
+  If a RegExp is used the matching groups will be available inside of
+  the context as `token_match`.
+
+* callback: JavaScript function to invoke when the user navigates to
+  the screen. The function will be passed a link:#ScreenContext[screen context].
+
 [[self_url]]
 === self.url()
 Returns a URL within the plugin's URL space. If invoked with no
@@ -282,7 +303,7 @@ context.get(function (result) {
 
 [[context_go]]
 === context.go()
-Go to a page. Shorthand for link:#Gerrit_go[`Gerrit.go()`].
+Go to a screen. Shorthand for link:#Gerrit_go[`Gerrit.go()`].
 
 [[context_hide]]
 === context.hide()
@@ -402,7 +423,7 @@ loaded the change.
 When the action is invoked on a specific project,
 the name of the project.
 
-== Action Context HTML Helpers
+=== HTML Helpers
 The link:#ActionContext[action context] includes some HTML helper
 functions to make working with DOM based widgets less painful.
 
@@ -446,6 +467,80 @@ functions to make working with DOM based widgets less painful.
 
 * `msg(label)`: a new label.
 
+
+[[ScreenContext]]
+== Screen Context
+A new screen context is passed to the `screen` callback function
+each time the user navigates to a matching URL.
+
+[[screen_body]]
+=== screen.body
+Empty HTML `<div>` node the plugin should add its content to.  The
+node is already attached to the document, but is invisible.  Plugins
+must call `screen.show()` to display the DOM node.  Deferred display
+allows an implementor to partially populate the DOM, make remote HTTP
+requests, finish populating when the callbacks arrive, and only then
+make the view visible to the user.
+
+[[screen_token]]
+=== screen.token
+URL token fragment that activated this screen.  The value is identical
+to `screen.token_match[0]`.  If the URL is `/#/x/hello/list` the token
+will be `"list"`.
+
+[[screen_token_match]]
+=== screen.token_match
+Array of matching subgroups from the pattern specified to `screen()`.
+This is identical to the result of RegExp.exec. Index 0 contains the
+entire matching expression; index 1 the first matching group, etc.
+
+[[screen_onUnload]]
+=== screen.onUnload()
+Configures an optional callback to be invoked just before the screen
+is deleted from the browser DOM.  Plugins can use this callback to
+remove event listeners from DOM nodes, preventing memory leaks.
+
+.Signature
+[source,javascript]
+----
+screen.onUnload(callback)
+----
+
+* callback: JavaScript function to be invoked just before the
+  `screen.body` DOM element is removed from the browser DOM.
+  This event happens when the user navigates to another screen.
+
+[[screen.setTitle]]
+=== screen.setTitle()
+Sets the heading text to be displayed when the screen is visible.
+This is presented in a large bold font below the menus, but above the
+content in `screen.body`.  Setting the title also sets the window
+title to the same string, if it has not already been set.
+
+.Signature
+[source,javascript]
+----
+screen.setPageTitle(titleText)
+----
+
+[[screen.setWindowTitle]]
+=== screen.setWindowTitle()
+Sets the text to be displayed in the browser's title bar when the
+screen is visible.  Plugins should always prefer this method over
+trying to set `window.title` directly.  The window title defaults to
+the title given to `setTitle`.
+
+.Signature
+[source,javascript]
+----
+screen.setWindowTitle(titleText)
+----
+
+[[screen_show]]
+=== screen.show()
+Destroy the currently visible screen and display the plugin's screen.
+This method must be called after adding content to `screen.body`.
+
 [[Gerrit]]
 == Gerrit
 
@@ -518,7 +613,7 @@ encouraged to use `self.getPluginName()` whenever possible.
 
 [[Gerrit_go]]
 === Gerrit.go()
-Updates the web UI to display the view identified by the supplied
+Updates the web UI to display the screen identified by the supplied
 URL token. The URL token is the text after `#` in the browser URL.
 
 [source,javascript]
@@ -621,6 +716,27 @@ Gerrit.onAction(type, view_name, callback);
 * callback: JavaScript function to invoke when the user clicks. The
   function will be passed a link:#ActionContext[ActionContext].
 
+[[Gerrit_screen]]
+=== Gerrit.screen()
+Register a JavaScript callback to be invoked when the user navigates
+to an extension screen provided by the plugin. Extension screens are
+usually linked from the link:dev-plugins.html#top-menu-extensions[top menu].
+The callback can populate the DOM with the screen's contents.
+
+.Signature
+[source,javascript]
+----
+Gerrit.screen(pattern, callback);
+----
+
+* pattern: URL token pattern to identify the screen. Argument can be
+  either a string (`'index'`) or a RegExp object (`/list\/(.*)/`).
+  If a RegExp is used the matching groups will be available inside of
+  the context as `token_match`.
+
+* callback: JavaScript function to invoke when the user navigates to
+  the screen. The function will be passed link:#ScreenContext[screen context].
+
 [[Gerrit_refresh]]
 === Gerrit.refresh()
 Redisplays the current web UI view, refreshing all information.

gerrit-gwtui/src/main/java/com/google/gerrit/client/Dispatcher.java

@@ -60,6 +60,7 @@ import com.google.gerrit.client.admin.ProjectDashboardsScreen;
 import com.google.gerrit.client.admin.ProjectInfoScreen;
 import com.google.gerrit.client.admin.ProjectListScreen;
 import com.google.gerrit.client.admin.ProjectScreen;
+import com.google.gerrit.client.api.ExtensionScreen;
 import com.google.gerrit.client.change.ChangeScreen2;
 import com.google.gerrit.client.changes.AccountDashboardScreen;
 import com.google.gerrit.client.changes.ChangeScreen;
@@ -226,6 +227,9 @@ public class Dispatcher {
     } else if (matchPrefix("/c/", token)) {
       change(token);
 
+    } else if (matchPrefix("/x/", token)) {
+      extension(token);
+
     } else if (matchExact(MINE, token)) {
       Gerrit.display(token, mine(token));
 
@@ -564,6 +568,15 @@ public class Dispatcher {
     }
   }
 
+  private static void extension(final String token) {
+    ExtensionScreen view = new ExtensionScreen(skip(token));
+    if (view.isFound()) {
+      Gerrit.display(token, view);
+    } else {
+      Gerrit.display(token, new NotFoundScreen());
+    }
+  }
+
   private static boolean isChangeScreen2() {
     if (!Gerrit.getConfig().getNewFeatures()) {
       return false;

gerrit-gwtui/src/main/java/com/google/gerrit/client/Gerrit.java

@@ -505,12 +505,9 @@ public class Gerrit implements EntryPoint {
     body = new ViewSite<Screen>() {
       @Override
       protected void onShowView(Screen view) {
-        lastViewToken = History.getToken();
         String token = view.getToken();
-        if (!token.equals(lastViewToken)) {
+        History.newItem(token, false);
-          History.newItem(token, false);
+        dispatchHistoryHooks(token);
-          dispatchHistoryHooks(token);
-        }
 
         if (view instanceof ChangeListScreen) {
           lastChangeListToken = token;
@@ -518,6 +515,7 @@ public class Gerrit implements EntryPoint {
 
         super.onShowView(view);
         view.onShowView();
+        lastViewToken = token;
       }
     };
     gBody.add(body);

gerrit-gwtui/src/main/java/com/google/gerrit/client/api/ApiGlue.java

@@ -15,8 +15,6 @@
 package com.google.gerrit.client.api;
 
 import com.google.gerrit.client.Gerrit;
-import com.google.gerrit.client.rpc.NativeString;
-import com.google.gwt.core.client.GWT;
 import com.google.gwt.core.client.JavaScriptObject;
 import com.google.gwt.core.client.JsArray;
 import com.google.gwt.user.client.History;
@@ -26,17 +24,20 @@ public class ApiGlue {
   private static String pluginName;
 
   public static void init() {
-    init0(GWT.getHostPageBaseURL(), NativeString.TYPE);
+    init0();
     ActionContext.init();
     Plugin.init();
     addHistoryHook();
   }
 
-  private static native void init0(String serverUrl, JavaScriptObject JsonString) /*-{
+  private static native void init0() /*-{
+    var serverUrl = @com.google.gwt.core.client.GWT::getHostPageBaseURL()();
+    var ScreenDefinition = @com.google.gerrit.client.api.ExtensionScreen.Definition::TYPE;
     $wnd.Gerrit = {
-      JsonString: JsonString,
+      JsonString: @com.google.gerrit.client.rpc.NativeString::TYPE,
       events: {},
       plugins: {},
+      screens: {},
       change_actions: {},
       revision_actions: {},
       project_actions: {},
@@ -63,6 +64,12 @@ public class ApiGlue {
         if ('change' == t) this.change_actions[i]=c;
         else if ('revision' == t) this.revision_actions[i]=c;
         else if ('project' == t) this.project_actions[i]=c;
+        else if ('screen' == t) _screen(p,t,c);
+      },
+      screen: function(r,c){this._screen(this.getPluginName(),r,c)},
+      _screen: function(p,r,c){
+        var s = new ScreenDefinition(r,c);
+        (this.screens[p] || (this.screens[p]=[])).push(s);
       },
 
       url: function (d) {

gerrit-gwtui/src/main/java/com/google/gerrit/client/api/ExtensionScreen.java

@@ -0,0 +1,139 @@
+// Copyright (C) 2013 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.client.api;
+
+import com.google.gerrit.client.rpc.Natives;
+import com.google.gerrit.client.ui.Screen;
+import com.google.gwt.core.client.JavaScriptObject;
+import com.google.gwt.core.client.JsArray;
+import com.google.gwt.core.client.JsArrayString;
+import com.google.gwt.dom.client.Element;
+
+/** Screen contributed by a plugin. */
+public class ExtensionScreen extends Screen {
+  private Context ctx;
+
+  public ExtensionScreen(String token) {
+    String name;
+    String rest;
+    int s = token.indexOf('/');
+    if (0 < s) {
+      name = token.substring(0, s);
+      rest = token.substring(s + 1);
+    } else {
+      name = token;
+      rest = "";
+    }
+    ctx = create(name, rest);
+  }
+
+  private Context create(String name, String rest) {
+    for (Definition def : Natives.asList(Definition.get(name))) {
+      JsArrayString m = def.match(rest);
+      if (m != null) {
+        return Context.create(def, this, m);
+      }
+    }
+    return null;
+  }
+
+  public boolean isFound() {
+    return ctx != null;
+  }
+
+  @Override
+  protected void onLoad() {
+    super.onLoad();
+    setHeaderVisible(false);
+    ctx.onLoad();
+  }
+
+  @Override
+  protected void onUnload() {
+    super.onUnload();
+    for (JavaScriptObject u : Natives.asList(ctx.unload())) {
+      ApiGlue.invoke(u);
+    }
+  }
+
+  static class Definition extends JavaScriptObject {
+    static final JavaScriptObject TYPE = init();
+    private static native JavaScriptObject init() /*-{
+      function ScreenDefinition(r, c) {
+        this.pattern = r;
+        this.onLoad = c;
+      };
+      return ScreenDefinition;
+    }-*/;
+
+    static native JsArray<Definition> get(String n)
+    /*-{ return $wnd.Gerrit.screens[n] || [] }-*/;
+
+    final native JsArrayString match(String t)
+    /*-{
+      var p = this.pattern;
+      if (p instanceof $wnd.RegExp) {
+        var m = p.exec(t);
+        return m && m[0] == t ? m : null;
+      }
+      return p == t ? [t] : null;
+    }-*/;
+
+    protected Definition() {
+    }
+  }
+
+  static class Context extends JavaScriptObject {
+    static final Context create(
+        Definition def,
+        ExtensionScreen view,
+        JsArrayString match) {
+      return create(TYPE, def, view, view.getBody().getElement(), match);
+    }
+
+    final native void onLoad() /*-{ this._d.onLoad(this) }-*/;
+    final native JsArray<JavaScriptObject> unload() /*-{ return this._u }-*/;
+
+    private static final native Context create(
+        JavaScriptObject T,
+        Definition d,
+        ExtensionScreen s,
+        Element e,
+        JsArrayString m)
+    /*-{ return new T(d,s,e,m) }-*/;
+
+    private static final JavaScriptObject TYPE = init();
+    private static final native JavaScriptObject init() /*-{
+      var T = function(d,s,e,m) {
+        this._d = d;
+        this._s = s;
+        this._u = [];
+        this.body = e;
+        this.token = m[0];
+        this.token_match = m;
+      };
+      T.prototype = {
+        setTitle: function(t){this._s.@com.google.gerrit.client.ui.Screen::setPageTitle(Ljava/lang/String;)(t)},
+        setWindowTitle: function(t){this._s.@com.google.gerrit.client.ui.Screen::setWindowTitle(Ljava/lang/String;)(t)},
+        show: function(){$entry(this._s.@com.google.gwtexpui.user.client.View::display()())},
+        onUnload: function(f){this._u.push(f)},
+      };
+      return T;
+    }-*/;
+
+    protected Context() {
+    }
+  }
+}

gerrit-gwtui/src/main/java/com/google/gerrit/client/api/Plugin.java

@@ -54,6 +54,7 @@ final class Plugin extends JavaScriptObject {
       refresh: @com.google.gerrit.client.api.ApiGlue::refresh(),
       on: function(e,f){G.on(e,f)},
       onAction: function(t,n,c){G._onAction(this.name,t,n,c)},
+      screen: function(p,c){G._screen(this.name,p,c)},
 
       url: function (u){return G.url(this._url(u))},
       get: function(u,b){@com.google.gerrit.client.api.ActionContext::get(Lcom/google/gerrit/client/rpc/RestApi;Lcom/google/gwt/core/client/JavaScriptObject;)(this._api(u),b)},

gerrit-gwtui/src/main/java/com/google/gerrit/client/ui/Screen.java

@@ -137,6 +137,10 @@ public abstract class Screen extends View {
     body.add(w);
   }
 
+  protected FlowPanel getBody() {
+    return body;
+  }
+
   protected void setTheme(final ThemeInfo t) {
     theme = t;
   }

gerrit-plugin-gwtui/src/main/java/com/google/gerrit/Plugin.gwt.xml

@@ -14,6 +14,8 @@
  limitations under the License.
 -->
 <module>
+  <inherits name="com.google.gwt.json.JSON"/>
+
   <define-linker name="gerrit_plugin" class="com.google.gerrit.plugin.linker.GerritPluginLinker"/>
   <add-linker name="gerrit_plugin"/>
   <generate-with class="com.google.gerrit.plugin.rebind.PluginGenerator">

gerrit-plugin-gwtui/src/main/java/com/google/gerrit/plugin/client/Plugin.java

@@ -14,6 +14,7 @@
 
 package com.google.gerrit.plugin.client;
 
+import com.google.gerrit.plugin.client.screen.Screen;
 import com.google.gwt.core.client.GWT;
 import com.google.gwt.core.client.JavaScriptObject;
 
@@ -49,6 +50,35 @@ public final class Plugin extends JavaScriptObject {
   public final native void refresh()
   /*-{ return this.refresh() }-*/;
 
+  /**
+   * Register a screen displayed at {@code /#/x/plugin/token}.
+   *
+   * @param token literal anchor token appearing after the plugin name. For
+   *        regular expression matching use {@code screenRegex()} .
+   * @param entry callback function invoked to create the screen widgets.
+   */
+  public final void screen(String token, Screen.EntryPoint entry) {
+    screen(token, wrap(entry));
+  }
+
+  private final native void screen(String t, JavaScriptObject e)
+  /*-{ this.screen(t, e) }-*/;
+
+  /**
+   * Register a screen displayed at {@code /#/x/plugin/regex}.
+   *
+   * @param regex JavaScript {@code RegExp} expression to match the anchor token
+   *        after the plugin name. Matching groups are exposed through the
+   *        {@code Screen} object passed into the {@code Screen.EntryPoint}.
+   * @param entry callback function invoked to create the screen widgets.
+   */
+  public final void screenRegex(String regex, Screen.EntryPoint entry) {
+    screenRegex(regex, wrap(entry));
+  }
+
+  private final native void screenRegex(String p, JavaScriptObject e)
+  /*-{ this.screen(new $wnd.RegExp(p), e) }-*/;
+
   protected Plugin() {
   }
 
@@ -56,4 +86,11 @@ public final class Plugin extends JavaScriptObject {
   native void _loaded() /*-{ this._loadedGwt() }-*/;
   private static native final Plugin install(String u)
   /*-{ return $wnd.Gerrit.installGwt(u) }-*/;
+
+  private static final native JavaScriptObject wrap(Screen.EntryPoint b) /*-{
+    return $entry(function(c){
+      b.@com.google.gerrit.plugin.client.screen.Screen.EntryPoint::onLoad(Lcom/google/gerrit/plugin/client/screen/Screen;)(
+        @com.google.gerrit.plugin.client.screen.Screen::new(Lcom/google/gerrit/plugin/client/screen/Screen$Context;)(c));
+    });
+  }-*/;
 }

gerrit-plugin-gwtui/src/main/java/com/google/gerrit/plugin/client/screen/Screen.java

@@ -0,0 +1,140 @@
+// Copyright (C) 2013 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.plugin.client.screen;
+
+import com.google.gwt.core.client.JavaScriptObject;
+import com.google.gwt.core.client.JsArrayString;
+import com.google.gwt.dom.client.Element;
+import com.google.gwt.user.client.ui.SimplePanel;
+import com.google.gwt.user.client.ui.Widget;
+
+/**
+ * Screen contributed by this plugin.
+ *
+ * Screens should be registered early at module load:
+ *
+ * <pre>
+ * &#064;Override
+ * public void onModuleLoad() {
+ *   Plugin.get().screen(&quot;hi&quot;, new Screen.EntryPoint() {
+ *     &#064;Override
+ *     public void onLoad(Screen screen) {
+ *       screen.setPageTitle(&quot;Hi&quot;);
+ *       screen.show(new Label(&quot;World&quot;));
+ *     }
+ *   });
+ * }
+ * </pre>
+ */
+public final class Screen extends SimplePanel {
+  /** Initializes a screen for display. */
+  public interface EntryPoint {
+    /**
+     * Invoked when the screen has been created, but not yet displayed.
+     * <p>
+     * The implementation should create a single widget to define the content of
+     * this screen and added it to the passed screen instance. When the screen
+     * is ready to be displayed, call {@link Screen#show()}.
+     * <p>
+     * To use multiple widgets, compose them in panels such as {@code FlowPanel}
+     * and add only the top level widget to the screen.
+     * <p>
+     * The screen is already attached to the browser DOM in an invisible area.
+     * Any widgets added to the screen will immediately receive {@code onLoad()}.
+     * GWT will fire {@code onUnload()} when the screen is removed from the UI,
+     * generally caused by the user navigating to another screen.
+     *
+     * @param screen panel that will contain the screen widget.
+     */
+    public void onLoad(Screen screen);
+  }
+
+  static final class Context extends JavaScriptObject {
+    final native Element body() /*-{ return this.body }-*/;
+    final native JsArrayString token_match() /*-{ return this.token_match }-*/;
+    final native void show() /*-{ this.show() }-*/;
+    final native void setTitle(String t) /*-{ this.setTitle(t) }-*/;
+    final native void setWindowTitle(String t) /*-{ this.setWindowTitle(t) }-*/;
+    final native void detach(Screen s) /*-{
+      this.onUnload($entry(function(){
+        s.@com.google.gwt.user.client.ui.Widget::onDetach()();
+      }));
+    }-*/;
+
+    protected Context() {
+    }
+  }
+
+  private final Context ctx;
+
+  Screen(Context ctx) {
+    super(ctx.body());
+    this.ctx = ctx;
+    onAttach();
+    ctx.detach(this);
+  }
+
+  /** @return the token suffix after {@code "/#/x/plugin-name/"}. */
+  public final String getToken() {
+    return getToken(0);
+  }
+
+  /**
+   * @param group groups range from 1 to {@code getTokenGroups() - 1}. Token
+   *        group 0 is the entire token, see {@link #getToken()}.
+   * @return the token from the regex match group.
+   */
+  public final String getToken(int group) {
+    return ctx.token_match().get(group);
+  }
+
+  /** @return total number of token groups. */
+  public final int getTokenGroups() {
+    return ctx.token_match().length();
+  }
+
+  /**
+   * Set the page title text; appears above the widget.
+   *
+   * @param titleText text to display above the widget.
+   */
+  public final void setPageTitle(String titleText) {
+    ctx.setTitle(titleText);
+  }
+
+  /**
+   * Set the window title text; appears in the browser window title bar.
+   *
+   * @param titleText text to display in the window title bar.
+   */
+  public final void setWindowTitle(String titleText) {
+    ctx.setWindowTitle(titleText);
+  }
+
+  /**
+   * Add the widget and immediately show the screen.
+   *
+   * @param w child containing the content.
+   */
+  public final void show(Widget w) {
+    setWidget(w);
+    ctx.show();
+  }
+
+  /** Show this screen in the web interface. */
+  public final void show() {
+    ctx.show();
+  }
+}

tools/gwt-constants.defs

@@ -4,7 +4,6 @@ GWT_COMPILER_OPTS = [
   '-optimize', '9',
   '-XdisableClassMetadata',
   '-XdisableCastChecking',
-  '-XenableClosureCompiler',
 ]
 
 GWT_PLUGIN_DEPS = [