Qt и OpenGL. Использует ли Qt OpenGL для прорисовки виджетов?

Плохо искал, в документации черным по английскому написано:

Since Qt 4.5, it is possible to replace the paint engines and paint devices used for widgets, pixmaps and the offscreen double buffer. By default the backends are:
Windows
Software Rasterizer
X11
X11
Mac OS X
CoreGraphics
Embedded
Software Rasterizer

Passing a command line parameter to the application, such as, -graphicssystem raster, specifies that Qt should use the software rasterizer for this application. The Software rasterizer is fully supported on all platforms.
> analogclock -graphicssystem raster
There is also a -graphicssystem opengl mode that uses OpenGL for all drawing. Currently, this engine is experimental as it does not draw everything correctly.
Qt also supports being configured using -graphicssystem raster|opengl in which case all applications will use the specified graphics system for its graphics.

Спасибо

Погодите, я нифига не понял. Так использует или нет?

может использовать, а может и не использовать. По дефолту не использует