pygame pyopengl resizing problem (under linux) [closed]

In test setup, i use no matrix transformations (screen coord space, -1.0 to 1.0) The shader is simply gl_Position = position.

After resize i get correctly scaled render, but viewport is cropped into old viewport range and shifted weirdly.

Do i miss something in this setup?

from OpenGL import GL
import pygame as pg

def main():
    import os, sys
    pg.init()
    os.environ['SDL_VIDEO_CENTERED'] = '1'
    screen = pg.display.set_mode((800,600),pg.HWSURFACE|pg.OPENGL|pg.DOUBLEBUF|pg.RESIZABLE)
    GL.glMatrixMode(GL.GL_PROJECTION)
    GL.glLoadIdentity()
    GL.glMatrixMode(GL.GL_MODELVIEW)
    GL.glLoadIdentity()
    running = True
    while running:
        GL.glClear(GL.GL_COLOR_BUFFER_BIT)
        GL.glBegin(GL.GL_TRIANGLES)
        GL.glVertex3f(-1.0, -1.0, 0.0)
        GL.glVertex3f(0.0, 1.0, 0.0)
        GL.glVertex3f(1.0, 0.0, 0.0)
        GL.glEnd()

        pg.display.flip()
        for ev in pg.event.get():
            if ev.type == pg.VIDEORESIZE:
                GL.glViewport(0, 0, ev.w, ev.h)
            if ev.type == pg.QUIT or (ev.type==pg.KEYDOWN and ev.key==pg.K_ESCAPE):
                running = False
                break
main()