3) It may have
effect in places it shouldn't.
Previews, background rendering, display of message chunks inside a special page,
etc might run the parser at many times other than a page view. This could lead
to inappropriate overwriting of the special page's title information.
An immediate example is that the "Editing XYZ" message gets overwritten
I've limited it to "$action == 'view'". That leaves some
I'll write a workaround.
That's still extremely wrong. You should not attempt to divine anything about or
affect the outside environment from the parser.
In many cases rendering for future views happens at save time. It might also
happen from a command-line maintenance script or other background job.
-- brion vibber (brion @