Add toolbar plugin technology.

source/website/index.js

@@ -2,15 +2,31 @@ import { SetExternalLibLocation } from '../engine/io/externallibs.js';
 import { Embed } from './embed.js';
 import { Website } from './website.js';
 import { SetEventHandler } from './eventhandler.js';
-
 import { PluginType, RegisterPlugin } from './pluginregistry.js';
-export { PluginType, RegisterPlugin };
+
+import * as Engine from '../engine/main.js';
+export { Engine };
+
+import { ButtonDialog } from './dialog.js';
+export const UI = {
+    ButtonDialog
+};
 
 export function SetWebsiteEventHandler (eventHandler)
 {
     SetEventHandler (eventHandler   );
 }
 
+export function RegisterHeaderPlugin (plugin)
+{
+    RegisterPlugin (PluginType.Header, plugin);
+}
+
+export function RegisterToolbarPlugin (plugin)
+{
+    RegisterPlugin (PluginType.Toolbar, plugin);
+}
+
 export function StartWebsite (externalLibLocation)
 {
     SetExternalLibLocation (externalLibLocation);

source/website/pluginregistry.js

@@ -2,7 +2,8 @@ let plugins = new Map ();
 
 export const PluginType =
 {
-    Header : 1
+    Header : 1,
+    Toolbar : 2
 };
 
 export function RegisterPlugin (type, plugin)

source/website/website.js

@@ -594,6 +594,20 @@ export class Website
             ShowSharingDialog (importer.GetFileList (), this.settings, this.viewer);
         });
 
+        EnumeratePlugins (PluginType.Toolbar, (plugin) => {
+            plugin.registerButtons ({
+                createSeparator : (icon, title, classNames) => {
+                    AddSeparator (this.toolbar, icon, title, classNames);
+                },
+                createButton : (icon, title, classNames, onClick) => {
+                    AddButton (this.toolbar, icon, title, classNames, onClick);
+                },
+                getModel : () => {
+                    return this.model;
+                }
+            });
+        });
+
         this.parameters.fileInput.addEventListener ('change', (ev) => {
             if (ev.target.files.length > 0) {
                 HandleEvent ('model_load_started', 'open_file');