If nWidth or nHeight is zero, CreateBitmap returns the handle to a 1- by 1-pixel, monochrome bitmap.

reactos/subsys/win32k/objects

diff -u -r1.55 -r1.56
--- bitmaps.c	19 Feb 2004 21:12:10 -0000	1.55
+++ bitmaps.c	20 Feb 2004 07:45:58 -0000	1.56
@@ -16,7 +16,7 @@

  *  along with this program; if not, write to the Free Software
  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */

-/* $Id: bitmaps.c,v 1.55 2004/02/19 21:12:10 weiden Exp $ */

+/* $Id: bitmaps.c,v 1.56 2004/02/20 07:45:58 royce Exp $ */

 #undef WIN32_LEAN_AND_MEAN
 #include <windows.h>
 #include <stdlib.h>

@@ -249,7 +249,8 @@

   /* Check parameters */
   if (!Height || !Width)
   {

-    return 0;

+    Width = 1;
+    Height = 1;

   }
   if (Planes != 1)
   {