[Themes] Revert theme settings when cancelling out of the themes dialog

src/view/ThemeSettings.js

@@ -120,6 +120,9 @@ define(function (require, exports, module) {
                 Object.keys(newSettings).forEach(function (setting) {
                     prefs.set(setting, newSettings[setting]);
                 });
+            } else if (id === "cancel") {
+                // Make sure we revert any changes to theme selection
+                prefs.set("themes", currentSettings.themes);
             }
         });
     }