fix ref problem with gc's from the gc cache. fixes bug 32120

gfx/src/gtk/nsGCCache.cpp

@@ -96,12 +96,12 @@ GdkGC *nsGCCache::GetGCFromDW(GdkWindow *window, GdkGCValues *gcv, GdkGCValuesMa
         if (gc_cache[i].clipRegion &&
             gdk_region_equal(clipRegion, gc_cache[i].clipRegion)) {
           //          printf("found GC in cache %i\n", ++numCalls);
-          return gc_cache [i].gc;
+          return gdk_gc_ref(gc_cache[i].gc);
         }
       } else {
         if(!gc_cache[i].clipRegion)
           //          printf("found GC in cache (no region) %i\n", ++numCalls);
-          return gc_cache [i].gc;
+          return gdk_gc_ref(gc_cache[i].gc);
       }
   }
   
@@ -139,7 +139,7 @@ GdkGC *nsGCCache::GetGCFromDW(GdkWindow *window, GdkGCValues *gcv, GdkGCValuesMa
 
     gc_cache [this_slot].gc = gc;
     
-    return gc;
+    return gdk_gc_ref(gc);
   }
 }
 

gfx/src/gtk/nsRenderingContextGTK.cpp

@@ -485,6 +485,10 @@ void nsRenderingContextGTK::UpdateGC()
   GdkGCValues values;
   GdkGCValuesMask valuesMask;
 
+  if (mGC)
+    gdk_gc_unref(mGC);
+
+
   memset(&values, 0, sizeof(GdkGCValues));
 
   values.font = mCurrentFont;