Bonjour,
J'ai le code suivant pour créer plusieurs context.
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    int pf, maxpf;
 PIXELFORMATDESCRIPTOR pfd;
    LAYERPLANEDESCRIPTOR  lpd;  /* layer plane descriptor */
    int   nEntries = 2;   /* number of entries in palette */
    COLORREF crEntries[2] = {  /* entries in custom palette */
      0x00000000,   /* black (ref #0 = transparent) */
      0x00ff0000,   /* blue */
    };
    /* get the maximum number of pixel formats */
    maxpf = DescribePixelFormat(hDC, 0, 0, NULL);
    /* find an overlay layer descriptor */
    for(pf = 0; pf < maxpf; pf++) {
        DescribePixelFormat(hDC, pf, sizeof(PIXELFORMATDESCRIPTOR), &pfd);
 /* the bReserved field of the PIXELFORMATDESCRIPTOR contains the
    number of overlay/underlay planes */
 if (pfd.bReserved > 0) {
   /* aha! This format has overlays/underlays */
   wglDescribeLayerPlane(hDC, pf, 1,
    sizeof(LAYERPLANEDESCRIPTOR), &lpd);
   if (lpd.dwFlags & LPD_SUPPORT_OPENGL  &&     lpd.dwFlags & flags)
     {
       goto found;
     }
 }
    }
found:
    /* now get the "normal" pixel format descriptor for the layer */
    DescribePixelFormat(hDC, pf, sizeof(PIXELFORMATDESCRIPTOR), &pfd);
 
    /* set the pixel format */
    if(SetPixelFormat(hDC, pf, &pfd) == FALSE) {
 MessageBox(NULL,
     "SetPixelFormat() failed:  Cannot set format specified.",
     "Error", MB_OK);
        return 0;
    }
 
    /* set up the layer palette */
    wglSetLayerPaletteEntries(hDC, 1, 0, nEntries, crEntries);
 
    /* realize the palette */
    wglRealizeLayerPalette(hDC, 1, TRUE);
 
    /* announce what we've got */
    printf("Number of overlays = %d\n", pfd.bReserved);
    printf("Color bits in the overlay = %d\n", lpd.cColorBits);
 
    return pf;
J'ai donc le message d'erreur "Hardware does not support overlay planes." (provenant du code).
A quoi cela est dû?

Je vous remercie.