Qt QML Simple Layout

Main.qml

import QtQuick 2.12
import QtQuick.Window 2.12
import QtQuick.Controls 2.4
import QtQuick.Layouts 1.3

Window {
  id: window_
  visible: true
  visibility: Window.Maximized
  title: qsTr("Title")
  color: "gray"

  ColumnLayout {
    id: column_layout_

    width: window_.width / 1.15;
    height: window_.height / 1.15

    // anchors set
    anchors.horizontalCenter: parent.horizontalCenter
    anchors.verticalCenter: parent.verticalCenter

    // ----- Blue Table -----
    Rectangle {
      id: table_

      width:  column_layout_.width
      height: column_layout_.height - row_layout_.height
      anchors.horizontalCenter: parent.horizontalCenter

      border.width: 10
      border.color: "white"
      color: "royalblue"
    }

    // ----- Button Layout -----
    RowLayout {
      id: row_layout_

      Layout.alignment: Qt.AlignHCenter | Qt.AlignVCenter
      anchors.top: table_.bottom
      anchors.horizontalCenter: parent.horizontalCenter

      // ----- Button PAUSE -----
      Rectangle {
        id: button_pause

        width: 100; height: 30; radius: 5; border.width: 5; border.color: "lightblue"
        Text {
          text: qsTr("PAUSE")

          anchors.horizontalCenter: parent.horizontalCenter
          anchors.verticalCenter: parent.verticalCenter
        }
      }

      // ----- Button START -----
      Rectangle {
        id: button_start

        width: 100; height: 30; radius: 5; border.width: 5; border.color: "lightblue"
        Text {
          text: qsTr("START")
          anchors.horizontalCenter: parent.horizontalCenter
          anchors.verticalCenter: parent.verticalCenter
        }
      }

      // ----- Button STOP -----
      Rectangle {
        id: button_stop

        width: 100; height: 30; radius: 5; border.width: 5; border.color: "lightblue"
        Text {
          text: qsTr("STOP")
          anchors.horizontalCenter: parent.horizontalCenter
          anchors.verticalCenter: parent.verticalCenter
        }
      }

    } /// RowLayout

  } /// ColumnLayout
}