openUntitledTab (selected = true, markdown = '') {
    // TODO: Don't allow new files if quitting.
    if (this.lifecycle === WindowLifecycle.QUITTED) return

    if (this.lifecycle === WindowLifecycle.READY) {
      const { browserWindow } = this
      browserWindow.webContents.send('mt::new-untitled-tab', selected, markdown)
    } else {
      this._markdownToOpen.push(markdown)
    }
  }
Open a new untitled tab optional with a markdown string.

@param {[boolean]} selected Whether the tab should become the selected tab (true if not set).
@param {[string]} markdown The markdown string.