fix monogfx example

docs/source/todo.rst

@@ -2,6 +2,7 @@ TODO
 ====
 
 Bug: monogfx circle, plot and line drawing with INVERT mode is broken (garbage pixels)
+     broken since commit "optimize monogfx.plot() to use a *40 lookup table in lores mode."
 
 
 STRUCTS: are being developed in their own separate branch for now, called "structs".

examples/cx16/testmonogfx.p8

@@ -246,7 +246,7 @@ doublebuffer {
             monogfx.circle(cx, 219, 20, true)
             monogfx.text(cx+20, 225, true, conv.str_uw(cx))
             cx++
-            monogfx.swap_buffers()
+            monogfx.swap_buffers(true)
         }
     }
 }