4 files changed, 30 insertions, 2 deletions
diff --git a/platform/windows/mupdfwinrt/Cache.cpp b/platform/windows/mupdfwinrt/Cache.cpp
index d2567bc2..d5108a7c 100644
--- a/platform/windows/mupdfwinrt/Cache.cpp
+++ b/platform/windows/mupdfwinrt/Cache.cpp
@@ -48,7 +48,10 @@ void Cache::Add(int value, int width_in, int height_in, fz_display_list *dlist,
 
 		tail = prev_entry;
 
-		/* Decrement the caches rc of this list */
+		/* Decrement the caches rc of this list. It is gone from cache but
+		   may still be in use by other threads, when threads are done they 
+		   should decrement and it should be freed at that time. See 
+		   ReleaseDisplayLists in muctx class */
 		fz_drop_display_list(mu_ctx, curr_entry->dlist);
 		delete curr_entry;
 		size--;
@@ -75,6 +78,8 @@ void Cache::Add(int value, int width_in, int height_in, fz_display_list *dlist,
 		head = new_entry;
 	}
 	size++;
+	/* Everytime we add an entry, we are also using it. Increment rc. See above */
+	fz_keep_display_list(mu_ctx, dlist);
 }
 
 fz_display_list* Cache::Use(int value, int *width_out, int *height_out, fz_context *mu_ctx)
@@ -109,6 +114,9 @@ fz_display_list* Cache::Use(int value, int *width_out, int *height_out, fz_conte
 		}
 		*width_out = curr_entry->width;
 		*height_out = curr_entry->height;
+		/* We must increment our reference to this one to ensure it is not 
+		   freed when removed from the cache. See above comments */
+		fz_keep_display_list(mu_ctx, curr_entry->dlist);
 		return curr_entry->dlist;
 	}
 	else
diff --git a/platform/windows/mupdfwinrt/muctx.cpp b/platform/windows/mupdfwinrt/muctx.cpp
index fbcb01f3..e51ea403 100644
--- a/platform/windows/mupdfwinrt/muctx.cpp
+++ b/platform/windows/mupdfwinrt/muctx.cpp
@@ -531,6 +531,21 @@ fz_display_list * muctx::CreateDisplayList(int page_num, int *width, int *height
 	return dlist;
 }
 
+void muctx::ReleaseDisplayLists(void *opdlist, void *opannotlist)
+{
+	fz_display_list *dlist = (fz_display_list*) opdlist;
+	fz_display_list *annotlist = (fz_display_list*) opannotlist;
+
+	if (dlist != NULL)
+	{
+		fz_drop_display_list(mu_ctx, dlist);
+	}
+	if (annotlist != NULL)
+	{
+		fz_drop_display_list(mu_ctx, annotlist);
+	}
+}
+
 /* A special version which will create the display list AND get the information
    that we need for various text selection tasks */
 fz_display_list * muctx::CreateDisplayListText(int page_num, int *width, int *height,
diff --git a/platform/windows/mupdfwinrt/muctx.h b/platform/windows/mupdfwinrt/muctx.h
index 16c44cd1..5b870543 100644
--- a/platform/windows/mupdfwinrt/muctx.h
+++ b/platform/windows/mupdfwinrt/muctx.h
@@ -101,6 +101,7 @@ public:
 	fz_display_list * CreateDisplayListText(int page_num, int *width,
 		int *height, fz_text_page **text, int *length);
 	fz_display_list * CreateAnnotationList(int page_num);
+	void ReleaseDisplayLists(void *dlist, void *annotlist);
 	int MeasurePage(int page_num, point_t *size);
 	point_t MeasurePage(fz_page *page);
 	unsigned int GetLinks(int page_num, sh_vector_link links_vec);
diff --git a/platform/windows/mupdfwinrt/mudocument.cpp b/platform/windows/mupdfwinrt/mudocument.cpp
index 060144b3..29df67c3 100644
--- a/platform/windows/mupdfwinrt/mudocument.cpp
+++ b/platform/windows/mupdfwinrt/mudocument.cpp
@@ -217,6 +217,8 @@ int mudocument::RenderPageBitmapSync(int page_num, int bmp_width, int bmp_height
 										&(bmp_data[0]), bmp_width, bmp_height,
 										scale, flipy, tile, { top_left.X, top_left.Y }, 
 										{ bottom_right.X, bottom_right.Y });
+		/* Done with lists */
+		mu_object.ReleaseDisplayLists(dlist, annotlist);
 	} 
 	else 
 	{
@@ -290,7 +292,9 @@ Windows::Foundation::IAsyncOperation<InMemoryRandomAccessStream^>^
 										  &(bmp_data[0]), bmp_width, bmp_height,
 										  scale, true, false, { 0.0, 0.0 }, 
 										  { (float) bmp_width, (float) bmp_height });
-		} 
+			/* Done with lists */
+			mu_object.ReleaseDisplayLists(dlist, annotlist);
+		}
 		else 
 		{ 
 			/* Rendering in immediate mode.  Keep lock in place */