title: QML: how to show a dialog after window open?
body: <p>I need to show the user a modal dialog before he or she starts working with the application. The application with dialog example:</p>
  
  <pre><code>import QtQuick 2.12
  import QtQuick.Window 2.12
  import QtQuick.Controls 2.12
  import QtQuick.Layouts 1.12
  import QtQuick.Dialogs 1.3
  
  Window {
      visible: true
      width: 640
      height: 480
      title: qsTr("Hello World")
  
      Button {
          text: "Show dialog"
          onClicked: profileDialog.open()
      }
  
      Dialog {
          id: profileDialog
          title: "Select profile"
          ColumnLayout {
              RadioButton {
                  checked: true
                  text: qsTr("First")
              }
              RadioButton {
                  text: qsTr("Second")
              }
              RadioButton {
                  text: qsTr("Third")
              }
          }
          standardButtons: StandardButton.Ok
      }
  
  }
  </code></pre>
  
  <p>This example shows dialog on the button click. But I need to do this when the application starts. How to show profileDialog on opening main window? Maybe there is some afterShow signal? But I cannot find such signal in the documentation.</p>