Currently, on X11, you will not get subpixel antialiasing when painting into a pixmap. This is due to the reasoning that the pixmap can be drawn with any transform later which would break the antialiasing.

However, on e.g. Windows, we depend on the fact that subpixel antialiasing is still turned on when drawing to pixmaps, because pixmaps are, for instance, used for UI elements in the XP style.

The paint engines should be consistent in this regard, so the X11 engine should be changed to accept cleartype to pixmaps. However, to minimize the impact for people who depend on the current behavior, we will wait until Qt gets the style strategy that allows you to explicitly turn off subpixel rendering for surfaces for which you know it won't work.