--- a\src\win\iupwin_canvas.c	Tue Jan 16 20:23:32 2018
+++ b\src\win\iupwin_canvas.c	Wed Jan 24 22:40:51 2018
@@ -579,6 +579,7 @@
       *result = 0;
       return 1;
     }
+    break;
   case WM_HSCROLL:
     /* only process the scrollbar if not a MDI client AND a standard scrollbar */
     if (!iupAttribGetBoolean(ih, "MDICLIENT") && lp == 0)
@@ -587,6 +588,7 @@
       *result = 0;
       return 1;
     }
+    break;
   case WM_SETFOCUS:
     if (!iupAttribGetBoolean(ih, "CANFOCUS"))
     {