But,

why with opengl is more slow ? I'm testing on:
Pentium4 1.70GHz
1Gb of Ram
GeForce4 MX 440 AGP 8x

Gentoo Linux 2007.0
xorg 1.3.0
NVIDIA Linux x86 Kernel Module 1.0-9639
glxgears = "1181.034 FPS"

only add "setViewport(new QGLWidget(QGLFormat(QGL::SampleBuffers)))" on my code. Is it correct ?