use WGL_SAMPLES_ARB, reduce extraneous output

panda/src/wgldisplay/wglGraphicsBuffer.cxx

@@ -289,7 +289,7 @@ make_pbuffer(HDC twindow_dc) {
       red_bits_i, green_bits_i, blue_bits_i, alpha_bits_i, 
       accum_red_bits_i, accum_green_bits_i, accum_blue_bits_i,
       accum_alpha_bits_i, depth_bits_i, 
-      stencil_bits_i, multisamples_i;
+      stencil_bits_i, sample_buffers_i, multisamples_i;
 
     iattrib_list[acceleration_i = ni++] = WGL_ACCELERATION_ARB;
     iattrib_list[pixel_type_i = ni++] = WGL_PIXEL_TYPE_ARB;
@@ -307,6 +307,7 @@ make_pbuffer(HDC twindow_dc) {
     iattrib_list[stencil_bits_i = ni++] = WGL_STENCIL_BITS_ARB;
 
     if (wglgsg->_supports_wgl_multisample) {
+      iattrib_list[sample_buffers_i = ni++] = WGL_SAMPLE_BUFFERS_ARB;
       iattrib_list[multisamples_i = ni++] = WGL_SAMPLES_ARB;
     }
 
@@ -355,6 +356,8 @@ make_pbuffer(HDC twindow_dc) {
     iattrib_list[ni++] = ivalue_list[stencil_bits_i];
 
     if (wglgsg->_supports_wgl_multisample) {
+      iattrib_list[ni++] = WGL_SAMPLE_BUFFERS_ARB;
+      iattrib_list[ni++] = ivalue_list[sample_buffers_i];
       iattrib_list[ni++] = WGL_SAMPLES_ARB;
       iattrib_list[ni++] = ivalue_list[multisamples_i];
     }

panda/src/wgldisplay/wglGraphicsPipe.cxx

@@ -374,8 +374,10 @@ choose_pfnum_advanced(const FrameBufferProperties &properties,
   if (!wglgsg->_wglChoosePixelFormatARB(window_dc, iattrib_list, fattrib_list,
                                         max_pformats, pformat, &nformats) ||
       nformats == 0) {
-    wgldisplay_cat.info()
-      << "Couldn't find a suitable advanced pixel format.\n";
+    if (wgldisplay_cat.is_debug()) {
+      wgldisplay_cat.info()
+        << "Couldn't find a suitable advanced pixel format.\n";
+    }
     return orig_pfnum;
   }