nixpkgs/pkgs/development/libraries/qt-5/5.6/qtbase/dlopen-gl.patch

Index: qtbase-opensource-src-5.5.1/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qglxintegration.cpp
===================================================================
--- qtbase-opensource-src-5.5.1.orig/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qglxintegration.cpp
+++ qtbase-opensource-src-5.5.1/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qglxintegration.cpp
@@ -563,7 +563,12 @@ void (*QGLXContext::getProcAddress(const
             {
                 extern const QString qt_gl_library_name();
 //                QLibrary lib(qt_gl_library_name());
+                // Check system library paths first
                 QLibrary lib(QLatin1String("GL"));
+                if (!lib.load()) {
+                    // Fallback to Mesa driver
+                    lib.setFileName(QLatin1String("@mesa_lib@/lib/libGL"));
+                }
                 glXGetProcAddressARB = (qt_glXGetProcAddressARB) lib.resolve("glXGetProcAddressARB");
             }
         }