ComboBox rotation doesn't rotate drop-down list

Qt 5.4.0 (i386-little_endian-ilp32 shared (dynamic) release build; by GCC 4.9.1) on "windows" 
OS: Windows 7 [winnt version 6.1.7601]

Architecture: x86_64; features: SSE2 SSE3 SSSE3 SSE4.1 SSE4.2 AVX AVX2 RTM HLE

Library info:
  PrefixPath: C:\Qt\Qt5.4.0\5.4\mingw491_32
  DocumentationPath: C:\Qt\Qt5.4.0\Docs\Qt-5.4
  HeadersPath: C:\Qt\Qt5.4.0\5.4\mingw491_32\include
  LibrariesPath: C:\Qt\Qt5.4.0\5.4\mingw491_32\lib
  LibraryExecutablesPath: C:\Qt\Qt5.4.0\5.4\mingw491_32\bin
  BinariesPath: C:\Qt\Qt5.4.0\5.4\mingw491_32\bin
  PluginsPath: C:\Qt\Qt5.4.0\5.4\mingw491_32\plugins
  ImportsPath: C:\Qt\Qt5.4.0\5.4\mingw491_32\imports
  Qml2ImportsPath: C:\Qt\Qt5.4.0\5.4\mingw491_32\qml
  ArchDataPath: C:\Qt\Qt5.4.0\5.4\mingw491_32
  DataPath: C:\Qt\Qt5.4.0\5.4\mingw491_32
  TranslationsPath: C:\Qt\Qt5.4.0\5.4\mingw491_32\translations
  ExamplesPath: C:\Qt\Qt5.4.0\Examples\Qt-5.4
  TestsPath: C:\Qt\Qt5.4.0\5.4\mingw491_32\tests

File selectors (increasing order of precedence):
  it_IT windows

Network:
  Using "OpenSSL 1.0.0k 5 Feb 2013", version: 0x100000bf

Platform capabilities: ThreadedPixmaps OpenGL ThreadedOpenGL WindowMasks MultipleWindows ForeignWindows NonFullScreenWindows NativeWidgets WindowManagement RasterGLSurface AllGLFunctionsQueryable

Style hints:
  mouseDoubleClickInterval: 500
  mousePressAndHoldInterval: 800
  startDragDistance: 10
  startDragTime: 500
  startDragVelocity: 0
  keyboardInputInterval: 400
  keyboardAutoRepeatRate: 32
  cursorFlashTime: 1060
  showIsFullScreen: 0
  passwordMaskDelay: 0
  passwordMaskCharacter: U+25CF
  fontSmoothingGamma: 1
  useRtlExtensions: 0
  setFocusOnTouchRelease: 0

Theme:
  Styles: WindowsVista,WindowsXP,Windows  System font: "MS Shell Dlg 2" 8
  General font : "MS Shell Dlg 2" 8
  Fixed font   : "Courier New" 9
  Title font   : "MS Shell Dlg 2" 8
  Smallest font: "MS Shell Dlg 2" 8
  Native file dialog

Screens: 2
# 0 "\\.\DISPLAY1" Depth: 32 Primary: yes
  Geometry: 1920x1080+0+0 Available: 1920x1040+0+0
  Virtual geometry: 3840x1080+0+0 Available: 3840x1080+0+0
  2 virtual siblings
  Physical size: 677x381 mm  Refresh: 60 Hz
  Physical DPI: 72.0355,72 Logical DPI: 96,96
  DevicePixelRatio: 1 Primary orientation: 2
  Orientation: 2 Native orientation: 0 OrientationUpdateMask: 0

# 1 "\\.\DISPLAY2" Depth: 32 Primary: no
  Geometry: 1920x1080+1920+0 Available: 1920x1080+1920+0
  Virtual geometry: 3840x1080+0+0 Available: 3840x1080+0+0
  2 virtual siblings
  Physical size: 677x381 mm  Refresh: 60 Hz
  Physical DPI: 72.0355,72 Logical DPI: 96,96
  DevicePixelRatio: 1 Primary orientation: 2
  Orientation: 2 Native orientation: 0 OrientationUpdateMask: 0

LibGL Vendor: Intel
Renderer: Intel(R) HD Graphics 4600
Version: 4.2.0 - Build 10.18.10.3383
Shading language: 4.20 - Build 10.18.10.3383
Format: Version: 4.2 Profile: 2 Swap behavior: 2 Buffer size (RGBA): 8,8,8,8 Depth buffer: 24 Stencil buffer: 8