NSTextView and key events, WAS: [ 101845 ] Pageup Pagedn do not work

[Willem Rein Oudshoorn]

Sorry to keep bothering you all, but perhaps someone can enlighten me
on some questions I have about the NSText system.

Consider the following diagram:

Picture
-------

  superclass
     |
     |
  NSTextView ---> delegate


Question
--------

Why is in -[NSTextView keyDown:]  the decission:

[non-editable] pass event to superclass, do NOT touch the 
               key down at all.
[editable]     pass to delegate or handle in NSTextView, but
               DO NOT PASS to superclass, even when the event
               can not be handled by the NSTextView + delegate.


Naive as I am, I would expect:

[non-editable]
[editable]
             *  Try to let the delegate handle the event
             *  Try to handle the event ourself,
             *  Send to superclass to continue traveling
                the NSResponder chain.


Reason I ask:

* In the NSTextView documentation provided by Apple I do not
  see any reference to special behaviour for non-editable 
  textviews with respect to the NSResponder chain.

* [the real reason]  If the situation is as I expect we can 
  quite easily implement pageup/pagedown for non-editable textviews.
  Namely:
  - Implement keyDown in NSScrollView (trivial and it works)
  - Applications that want to handle their own scrolling, 
    should register themself as delegate and handle the
    textView:doCommandBySelector: 
    

Wim Oudshoorn.