Add a drag and drop test client
diff --git a/clients/cairo-util.h b/clients/cairo-util.h
index 18fa2b7..f28ac5f 100644
--- a/clients/cairo-util.h
+++ b/clients/cairo-util.h
@@ -28,10 +28,10 @@
 
 void
 tile_mask(cairo_t *cr, cairo_surface_t *surface,
-	  int x, int y, int width, int height, int margin);
+	  int x, int y, int width, int height, int margin, int top_margin);
 
 void
 tile_source(cairo_t *cr, cairo_surface_t *surface,
-	    int x, int y, int width, int height, int margin);
+	    int x, int y, int width, int height, int margin, int top_margin);
 
 #endif