Make window transparent to mouse events outside MouseAreas?

NippyFlux

I know I might have some crazy ideas but I decide to share with you guys.

Basically I'm making a frameless semi-transparent application with QML. There are some buttons based on MouseArea that I want to click. Besides the buttons are some other (semi-transparent) visual components but I want them to ignore any mouse events (so that I can click at other applications below them).

Is this possible with the current QML framework (or in c++ side)?

Things I've tried so far:

Qt.WA_TransparentForMouseEvents . This sadly make my window ignore all mouse events and there doesn't seem to be anyway to catch them.
setMask on QWindow or QQuickWidget. The mask can correctly limit mouse event capturing but it also crops all visual contents.

Some sample code:

import QtQuick 2.8

Rectangle { // click through this
  color: Qt.rgba(1, 1, 1, 0.5)

  width: 640
  height: 480

  Rectangle { // click on this
    color: 'white'
    width: 50
    height: 50
    anchors.centerIn: parent

    MouseArea {
      anchors.fill: parent
      onClicked: console.log('click')
    }
  }
}