How to use @lumino/messaging - 10 common examples

protected attachWidget(widget: Widget): void {
    // Send a `'before-attach'` message if the parent is attached.
    if (this.parent!.isAttached) {
      MessageLoop.sendMessage(widget, Widget.Msg.BeforeAttach);
    }

    // Add the widget's node to the parent.
    this.parent!.node.appendChild(widget.node);

    // Send an `'after-attach'` message if the parent is attached.
    if (this.parent!.isAttached) {
      MessageLoop.sendMessage(widget, Widget.Msg.AfterAttach);
    }

    // Post a fit request for the parent widget.
    this.parent!.fit();
  }

previousWidget.hide();
    }

    // Show the current widget.
    if (currentWidget) {
      currentWidget.show();
    }

    // Emit the `currentChanged` signal for the tab panel.
    this._currentChanged.emit({
      previousIndex, previousWidget, currentIndex, currentWidget
    });

    // Flush the message loop on IE and Edge to prevent flicker.
    if (Platform.IS_EDGE || Platform.IS_IE) {
      MessageLoop.flush();
    }
  }

protected attachWidget(widget: Widget): void {
    // Send a `'before-attach'` message if the parent is attached.
    if (this.parent!.isAttached) {
      MessageLoop.sendMessage(widget, Widget.Msg.BeforeAttach);
    }

    // Add the widget's node to the parent.
    this.parent!.node.appendChild(widget.node);

    // Send an `'after-attach'` message if the parent is attached.
    if (this.parent!.isAttached) {
      MessageLoop.sendMessage(widget, Widget.Msg.AfterAttach);
    }
  }

createBody(value: Body): Widget {
      let body: Widget;
      if (typeof value === 'string') {
        body = new Widget({ node: document.createElement('span') });
        body.node.textContent = value;
      } else if (value instanceof Widget) {
        body = value;
      } else {
        body = ReactWidget.create(value);
        // Immediately update the body even though it has not yet attached in
        // order to trigger a render of the DOM nodes from the React element.
        MessageLoop.sendMessage(body, Widget.Msg.UpdateRequest);
      }
      body.addClass('jp-Dialog-body');
      Styling.styleNode(body.node);
      return body;
    }

protected moveWidget(fromIndex: number, toIndex: number, widget: Widget): void {
    // Send a `'before-detach'` message if the parent is attached.
    if (this.parent!.isAttached) {
      MessageLoop.sendMessage(widget, Widget.Msg.BeforeDetach);
    }

    // Remove the widget's node from the parent.
    this.parent!.node.removeChild(widget.node);

    // Send an `'after-detach'` and  message if the parent is attached.
    if (this.parent!.isAttached) {
      MessageLoop.sendMessage(widget, Widget.Msg.AfterDetach);
    }

    // Look up the next sibling reference node.
    let ref = this.parent!.node.children[toIndex];

    // Send a `'before-attach'` message if the parent is attached.
    if (this.parent!.isAttached) {
      MessageLoop.sendMessage(widget, Widget.Msg.BeforeAttach);
    }

    // Insert the widget's node before the sibling.
    this.parent!.node.insertBefore(widget.node, ref);

    // Send an `'after-attach'` message if the parent is attached.
    if (this.parent!.isAttached) {
      MessageLoop.sendMessage(widget, Widget.Msg.AfterAttach);

function openRootMenu(menu: Menu, x: number, y: number, forceX: boolean, forceY: boolean): void {
    // Ensure the menu is updated before attaching and measuring.
    MessageLoop.sendMessage(menu, Widget.Msg.UpdateRequest);

    // Get the current position and size of the main viewport.
    let px = window.pageXOffset;
    let py = window.pageYOffset;
    let cw = document.documentElement.clientWidth;
    let ch = document.documentElement.clientHeight;

    // Compute the maximum allowed height for the menu.
    let maxHeight = ch - (forceY ? y : 0);

    // Fetch common variables.
    let node = menu.node;
    let style = node.style;

    // Clear the menu geometry and prepare it for measuring.
    style.top = '';

protected detachWidget(index: number, widget: Widget): void {
    // Send a `'before-detach'` message if the parent is attached.
    if (this.parent!.isAttached) {
      MessageLoop.sendMessage(widget, Widget.Msg.BeforeDetach);
    }

    // Remove the widget's node from the parent.
    this.parent!.node.removeChild(widget.node);

    // Send an `'after-detach'` message if the parent is attached.
    if (this.parent!.isAttached) {
      MessageLoop.sendMessage(widget, Widget.Msg.AfterDetach);
    }
  }

if (previousTitle) {
      previousTitle.owner.hide();
    }

    // Show the current widget.
    if (currentTitle) {
      currentTitle.owner.show();
    }

    // Flush the message loop on IE and Edge to prevent flicker.
    if (Platform.IS_EDGE || Platform.IS_IE) {
      MessageLoop.flush();
    }

    // Schedule an emit of the layout modified signal.
    MessageLoop.postMessage(this, Private.LayoutModified);
  }

addWidget(widget: Widget, options: DockPanel.IAddOptions = {}): void {
    // Add the widget to the layout.
    if (this._mode === 'single-document') {
      (this.layout as DockLayout).addWidget(widget);
    } else {
      (this.layout as DockLayout).addWidget(widget, options);
    }

    // Schedule an emit of the layout modified signal.
    MessageLoop.postMessage(this, Private.LayoutModified);
  }

private _evtMouseUp(event: MouseEvent): void {
    // Do nothing if the left mouse button is not released.
    if (event.button !== 0) {
      return;
    }

    // Stop the event when releasing a handle.
    event.preventDefault();
    event.stopPropagation();

    // Finalize the mouse release.
    this._releaseMouse();

    // Schedule an emit of the layout modified signal.
    MessageLoop.postMessage(this, Private.LayoutModified);
  }