skip QPainter and paint the frame unscaled into the screenbuffer to align to GL look

unsupported for no reason. accessibility stuff.

also i heard somebody suggesting xrender as alternative to pot. to be removed GL 1.x support.
somebody has probably not considered the "but it doesn't support most effects" argument that will come up then.
so we just improve the numbers that somebody can then show ... ;-)

yes, zooms. works at really great speed on nvidia chip but maybe i should (though it seems ignored anyway) make the filter configurable nevertheless.