[gtk+] gdkglcontext-x11: Make sure to enable the scissor test

[Jasper St. Pierre <jstpierre src gnome org>]

commit 7312c01f62b701d01ed29fca33e9a05041bf5b2a
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Sat Nov 22 10:01:51 2014 -0800

    gdkglcontext-x11: Make sure to enable the scissor test

 gdk/x11/gdkglcontext-x11.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/gdk/x11/gdkglcontext-x11.c b/gdk/x11/gdkglcontext-x11.c
index 92d0b9e..171ad05 100644
--- a/gdk/x11/gdkglcontext-x11.c
+++ b/gdk/x11/gdkglcontext-x11.c
@@ -470,6 +470,8 @@ gdk_x11_gl_context_texture_from_surface (GdkGLContext *paint_context,
   glXBindTexImageEXT (glx_pixmap->display, glx_pixmap->drawable,
                      GLX_FRONT_LEFT_EXT, NULL);
 
+  glEnable (GL_SCISSOR_TEST);
+
   n_rects = cairo_region_num_rectangles (region);
   for (i = 0; i < n_rects; i++)
     {
@@ -509,6 +511,8 @@ gdk_x11_gl_context_texture_from_surface (GdkGLContext *paint_context,
       }
     }
 
+  glDisable (GL_SCISSOR_TEST);
+
   glXReleaseTexImageEXT (glx_pixmap->display, glx_pixmap->drawable,
                         GLX_FRONT_LEFT_EXT);