[gtk/fix-win32-shader-check] gdkglcontext-win32-wgl.c: Fix Cairo fallback check

[Chun-wei Fan <fanchunwei src gnome org>]

commit 75aa1a757b17eb8cef0d2cc23eca56d47e3ee45a
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Fri Sep 17 11:09:23 2021 +0800

    gdkglcontext-win32-wgl.c: Fix Cairo fallback check
    
    We were setting the WGL pixel format in GdkWin32Display too early, so the code
    does not bail out correctly when we retry establishing the WGL context.
    
    Fix this by pushing back setting the WGL pixel format only after it passes the
    shader availability check.
    
    Should fix issue #4257.

 gdk/win32/gdkglcontext-win32-wgl.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/gdk/win32/gdkglcontext-win32-wgl.c b/gdk/win32/gdkglcontext-win32-wgl.c
index 3d05fb8907..010436bd3e 100644
--- a/gdk/win32/gdkglcontext-win32-wgl.c
+++ b/gdk/win32/gdkglcontext-win32-wgl.c
@@ -288,7 +288,6 @@ gdk_win32_display_init_wgl (GdkDisplay  *display,
       return FALSE;
     }
 
-  display_win32->wgl_pixel_format = best_idx;
   display_win32->gl_version = epoxy_gl_version ();
 
   /* We must have OpenGL/WGL 2.0 or later, or have the GL_ARB_shader_objects extension */
@@ -307,6 +306,8 @@ gdk_win32_display_init_wgl (GdkDisplay  *display,
         }
     }
 
+  display_win32->wgl_pixel_format = best_idx;
+
   display_win32->hasWglARBCreateContext =
     epoxy_has_wgl_extension (hdc, "WGL_ARB_create_context");
   display_win32->hasWglEXTSwapControl =