monitor param

src/shaders.c

@@ -366,5 +366,8 @@ void shaders_apply(ShaderProgram program, Context context) {
     }
   }
 
-  use_program(program, program.frag_monitor_index, true, context);
+  use_program(program,
+              context.monitor ? program.frag_monitor_index
+                              : program.frag_output_index,
+              true, context);
 }