Why cursor is moved to 0,0 when I use setGeometry?

[PawlosCK]

I want to press left mouse button and move window to other position. Generally everything is ok, but I don't know, why cursor is moved to position 0,0.

        onPositionChanged:
        {
            if (mouse.buttons == Qt.LeftButton)
            {
                console.log("Mouse: X:Y: " + mouseX + ":" + mouseY)
                console.log("Window: X:Y: " + mainWindow.x + ":" + mainWindow.y)
                console.log(mapToGlobal(mouseX, mouseY))

                var windowGeometry = mapToGlobal(mouseX, mouseY)
                mainWindow.setGeometry(windowGeometry.x, windowGeometry.y , mainWindow.width, mainWindow.height)

            }
        }