--- Operating System, Graphics card ---
Windows 7 64 bit 8GB
nVidia gtx460 1GB


--- Blender version with error, and version that worked ---
Blender official 2.67 release


--- Short description of error ---
If you visit this link.
http://www.blender.org/documentation/blender_python_api_2_67_release/bpy.types.RenderEngine.html?highlight=view_update#bpy.types.RenderEngine.view_update

There is code for an example render engine.
I want to install a custom update viewport routine, but the view_update or view_draw never fires.

--- Steps for others to reproduce the error (preferably based on attached .blend file) ---
Add a view_update def to the example render engine and place a print statement in the def.
You will discover that event never fires even with repeated rendering or viewport resizes.

Do I need extra code to activate the view_update event or is this a Blender bug?