Window dump in state QmlContainerWindow "minimized":
-----------------------------------------------------

"5.5.0 windows"


showing  QmlContainerWindow parented TestMainWindow(0x30fa50, name = "TestMainWindow")
QmlContainerWindow::QmlContainerWindow QWindowContainer(0x7924470)
### 0
### QWidgets:
TestMainWindow/"TestMainWindow" [visible] [native: 0x4103ee] [top] [mapped] 335x100+640+276 0x8800f001 Qt::Window Qt::WindowTitleHint Qt::WindowSystemMenuHint Qt::WindowMinimizeButtonHint Qt::WindowMaximizeButtonHint Qt::WindowFullscreenButtonHint
  QWidgetWindow/"TestMainWindowWindow" [visible] [native: 0x4103ee] [top] [exposed] 335x100+640+276 0x8800f001 Qt::Window Qt::WindowTitleHint Qt::WindowSystemMenuHint Qt::WindowMinimizeButtonHint Qt::WindowMaximizeButtonHint Qt::WindowFullscreenButtonHint
  ....
     QWindowContainer [visible] [not mapped] 400x172+0+26 0x8800f000 Qt::WindowTitleHint Qt::WindowSystemMenuHint Qt::WindowMinimizeButtonHint Qt::WindowMaximizeButtonHint Qt::WindowFullscreenButtonHint

QmlContainerWindow/"QmlContainerWindow" [visible] [native: 0xd03d8] [top] [mapped] windowState=0x1 400x223+690+214 0x8800f001 Qt::Window Qt::WindowTitleHint Qt::WindowSystemMenuHint Qt::WindowMinimizeButtonHint Qt::WindowMaximizeButtonHint Qt::WindowFullscreenButtonHint
  QWidgetWindow/"QmlContainerWindowWindow" [visible] [native: 0xd03d8] [top] [exposed] windowState=1 400x223+690+214 0x8800f001 Qt::Window Qt::WindowTitleHint Qt::WindowSystemMenuHint Qt::WindowMinimizeButtonHint Qt::WindowMaximizeButtonHint Qt::WindowFullscreenButtonHint

  QRubberBand/"qt_rubberband" [hidden] [not mapped] 0x0+0+0 0x8800f000 Qt::WindowTitleHint Qt::WindowSystemMenuHint Qt::WindowMinimizeButtonHint Qt::WindowMaximizeButtonHint Qt::WindowFullscreenButtonHint
  QMenuBar/"menubar" [visible] [not mapped] 400x0+0+0 0x8800f000 Qt::WindowTitleHint Qt::WindowSystemMenuHint Qt::WindowMinimizeButtonHint Qt::WindowMaximizeButtonHint Qt::WindowFullscreenButtonHint
    QToolButton/"qt_menubar_ext_button" [hidden] [not mapped] 100x30+0+0 0x8800f000 Qt::WindowTitleHint Qt::WindowSystemMenuHint Qt::WindowMinimizeButtonHint Qt::WindowMaximizeButtonHint Qt::WindowFullscreenButtonHint
  QStatusBar/"statusbar" [visible] [not mapped] 400x25+0+198 0x8800f000 Qt::WindowTitleHint Qt::WindowSystemMenuHint Qt::WindowMinimizeButtonHint Qt::WindowMaximizeButtonHint Qt::WindowFullscreenButtonHint
    QSizeGrip [visible] [not mapped] 13x13+387+12 0x8800f000 Qt::WindowTitleHint Qt::WindowSystemMenuHint Qt::WindowMinimizeButtonHint Qt::WindowMaximizeButtonHint Qt::WindowFullscreenButtonHint
  QToolBar/"toolBar" [visible] [not mapped] 400x26+0+0 0x800 Qt::FramelessWindowHint
    QToolBarExtension/"qt_toolbar_ext_button" [hidden] [not mapped] 100x30+0+0 0x8800f000 Qt::WindowTitleHint Qt::WindowSystemMenuHint Qt::WindowMinimizeButtonHint Qt::WindowMaximizeButtonHint Qt::WindowFullscreenButtonHint
    QToolButton [visible] [not mapped] 94x22+12+2 0x8800f000 Qt::WindowTitleHint Qt::WindowSystemMenuHint Qt::WindowMinimizeButtonHint Qt::WindowMaximizeButtonHint Qt::WindowFullscreenButtonHint
  QWindowContainer [visible] [not mapped] 400x172+0+26 0x8800f000 Qt::WindowTitleHint Qt::WindowSystemMenuHint Qt::WindowMinimizeButtonHint Qt::WindowMaximizeButtonHint Qt::WindowFullscreenButtonHint
QMenu [hidden] [top] [not mapped] 100x30+0+0 0x8800f009 Qt::Window Qt::Popup Qt::WindowTitleHint Qt::WindowSystemMenuHint Qt::WindowMinimizeButtonHint Qt::WindowMaximizeButtonHint Qt::WindowFullscreenButtonHint

Windows:
### QWindows:
QWidgetWindow/"TestMainWindowWindow" [visible] [native: 0x4103ee] [top] [exposed] 335x100+640+276 0x8800f001 Qt::Window Qt::WindowTitleHint Qt::WindowSystemMenuHint Qt::WindowMinimizeButtonHint Qt::WindowMaximizeButtonHint Qt::WindowFullscreenButtonHint
QWindow [hidden] [top] 0x0+0+0 0x1 Qt::Window
QWidgetWindow/"QmlContainerWindowWindow" [visible] [native: 0xd03d8] [top] [exposed] windowState=1 400x223+690+214 0x8800f001 Qt::Window Qt::WindowTitleHint Qt::WindowSystemMenuHint Qt::WindowMinimizeButtonHint Qt::WindowMaximizeButtonHint Qt::WindowFullscreenButtonHint
  QQuickView [visible] [native: 0x10203e2] [exposed] 400x172+0+26 0x1 Qt::Window

Native:
0xd03d8 160x32+0+1000 [visible] style=0xb6cf0000 WS_POPUP WS_MINIMIZE WS_VISIBLE WS_CLIPSIBLINGS WS_CLIPCHILDREN WS_CAPTION WS_BORDER WS_DLGFRAME WS_SYSMENU WS_THICKFRAME WS_GROUP WS_TABSTOP WS_MINIMIZEBOX WS_MAXIMIZEBOX exStyle=0x100 WS_EX_WINDOWEDGE title="MainWindow" class="Qt5QWindowIcon"
  0x10203e2 400x172+0+1026 [visible] style=0x56000000 WS_CHILD WS_VISIBLE WS_CLIPSIBLINGS WS_CLIPCHILDREN class="Qt5QWindowOwnDCIcon"
0x10203e2 400x172+0+1026 [visible] style=0x56000000 WS_CHILD WS_VISIBLE WS_CLIPSIBLINGS WS_CLIPCHILDREN class="Qt5QWindowOwnDCIcon"
0x4103ee 353x145+631+240 [visible] style=0x96cf0000 WS_POPUP WS_VISIBLE WS_CLIPSIBLINGS WS_CLIPCHILDREN WS_CAPTION WS_BORDER WS_DLGFRAME WS_SYSMENU WS_THICKFRAME WS_GROUP WS_TABSTOP WS_MINIMIZEBOX WS_MAXIMIZEBOX exStyle=0x100 WS_EX_WINDOWEDGE title="5.5.0 windows" class="Qt5QWindowIcon"

The QQuickView has Qt::Window, but WS_CHILD .