Pretty sure we fixed this in mg, i think you need to wrap the readpixel call like this:
glPixelStorei(GL_PACK_ALIGNMENT, 1);
glReadPixels(0, 0, pixmapScreenShot->getW(), pixmapScreenShot->getH(),
GL_RGB, GL_UNSIGNED_BYTE, pixmapScreenShot->getPixels());
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);