Qt4/Qt5 neutral changes:

+ replace Q_WS_WIN with Q_OS_WIN
+ replace Q_WS_X11 with Q_OS_LINUX
+ replace Q_WS_MACX with Q_OS_MACX
+ set explicit cast to HWND

src/Gui/DlgMaterialPropertiesImp.cpp

@@ -52,7 +52,7 @@ DlgMaterialPropertiesImp::DlgMaterialPropertiesImp(const std::string& mat, QWidg
         this->diffuseColor->hide();
     }
 
-//#if !defined(Q_WS_MAC)
+//#if !defined(Q_OS_MAC)
     ambientColor->setAutoChangeColor(true);
     diffuseColor->setAutoChangeColor(true);
     emissiveColor->setAutoChangeColor(true);