Don't add a new workspace when the maximum workspaces limit is reached

It was previously possible to add a workspace above the maximum workspaces
limit by dragging an item to the "add workspace" button or using the middle
mouse button click.

Provide the user with feedback in the info bar when it is not possible to create
a new workspace or remove the current workspace.

https://bugzilla.gnome.org/show_bug.cgi?id=591645

js/ui/appDisplay.js

@@ -459,10 +459,12 @@ AppWellIcon.prototype = {
             this._onActivate(event);
         } else if (button == 2) {
             let newWorkspace = Main.overview.workspaces.addWorkspace();
-            newWorkspace.activate(global.get_current_time());
-            this.emit('launching');
-            this.app.open_new_window();
-            Main.overview.hide();
+            if (newWorkspace != null) {
+                newWorkspace.activate(global.get_current_time());
+                this.emit('launching');
+                this.app.open_new_window();
+                Main.overview.hide();
+            }
         } else if (button == 3) {
             // Don't bind to the right click here; we want left click outside the
             // area to deactivate as well.

js/ui/workspacesView.js

@@ -11,6 +11,8 @@ const Pango = imports.gi.Pango;
 const Shell = imports.gi.Shell;
 const St = imports.gi.St;
 const Signals = imports.signals;
+const Gettext = imports.gettext.domain('gnome-shell');
+const _ = Gettext.gettext;
 
 const DND = imports.ui.dnd;
 const Lightbox = imports.ui.lightbox;
@@ -233,15 +235,31 @@ GenericWorkspacesView.prototype = {
     },
 
     addWorkspace: function() {
+        if (!this.canAddWorkspace()) {
+            Main.overview.infoBar.setMessage(_("Can't add a new workspace because maximum workspaces limit has been reached."));
+            return null;
+        }
+
+        return global.screen.append_new_workspace(false, global.get_current_time());
+    },
+
+    _getWorkspaceIndexToRemove: function() {
         throw new Error("Not implemented");
     },
 
     canRemoveWorkspace: function() {
-        throw new Error("Not implemented");
+        return this._getWorkspaceIndexToRemove() > 0;
     },
 
     removeWorkspace: function() {
-        throw new Error("Not implemented");
+        if (!this.canRemoveWorkspace()) {
+            Main.overview.infoBar.setMessage(_("Can't remove the first workspace."));
+            return;
+        }
+        let index = this._getWorkspaceIndexToRemove();
+        let metaWorkspace = this._workspaces[index].metaWorkspace;
+        global.screen.remove_workspace(metaWorkspace,
+                                       global.get_current_time());
     },
 
     updateWorkspaces: function() {
@@ -261,7 +279,9 @@ GenericWorkspacesView.prototype = {
     },
 
     _acceptNewWorkspaceDrop: function(source, dropActor, x, y, time) {
-        this.addWorkspace();
+        let ws = this.addWorkspace();
+        if (ws == null)
+            return false;
         return this.acceptNewWorkspaceDrop(source, dropActor, x, y, time);
     }
 };
@@ -444,19 +464,8 @@ MosaicView.prototype = {
         return null;
     },
 
-    addWorkspace: function() {
-        return global.screen.append_new_workspace(false, global.get_current_time());
-    },
-
-    canRemoveWorkspace: function() {
-        return global.screen.n_workspaces > 1;
-    },
-
-    removeWorkspace: function() {
-        let removedIndex = this._workspaces.length - 1;
-        let metaWorkspace = this._workspaces[removedIndex].metaWorkspace;
-        global.screen.remove_workspace(metaWorkspace,
-                                       global.get_current_time());
+    _getWorkspaceIndexToRemove: function() {
+        return this._workspaces.length - 1;
     }
 };
 
@@ -1377,10 +1386,6 @@ SingleView.prototype = {
         return actor;
     },
 
-    canRemoveWorkspace: function() {
-        return global.screen.get_active_workspace_index() != 0;
-    },
-
     _updatePanelVisibility: function() {
         let showSwitches = (global.screen.n_workspaces > 1);
         if (this._scroll != null) {
@@ -1392,17 +1397,15 @@ SingleView.prototype = {
     },
 
     addWorkspace: function() {
-        let ws = global.screen.append_new_workspace(false,
-                                                    global.get_current_time());
-        ws.activate(global.get_current_time());
+        let ws = GenericWorkspacesView.prototype.addWorkspace.call(this);
+        if (ws != null)
+            ws.activate(global.get_current_time());
+
         return ws;
     },
 
-    removeWorkspace: function() {
-        let removedIndex = global.screen.get_active_workspace_index();
-        let metaWorkspace = this._workspaces[removedIndex].metaWorkspace;
-        global.screen.remove_workspace(metaWorkspace,
-                                       global.get_current_time());
+    _getWorkspaceIndexToRemove: function() {
+        return global.screen.get_active_workspace_index();
     }
 };
 
@@ -1531,7 +1534,6 @@ WorkspacesControls.prototype = {
     _setButtonSensitivity: function(button, sensitive) {
         if (button == null)
             return;
-        button.reactive = sensitive;
         button.opacity = sensitive ? 255 : 85;
     },
 

po/POTFILES.in

@@ -12,6 +12,7 @@ js/ui/placeDisplay.js
 js/ui/runDialog.js
 js/ui/statusMenu.js
 js/ui/windowAttentionHandler.js
+js/ui/workspacesView.js
 src/gdmuser/gdm-user.c
 src/shell-global.c
 src/shell-uri-util.c