Re: Subclassing NSOutlineView causes failure of window to become main or key

FROM : Dennis Hartigan-O'Connor
DATE : Mon Mar 03 02:15:33 2008

Thanks, John,

In all these cases, I can use NSLog to print to the Run Log--but no
errors are printed there by the system.

In all cases, the Console Log is blank.

In cases where the window doesn't become main or key, if I attach the
debugger I find that the thread list looks exactly the SAME as when the
window does become main or key:

#0    0x9000b348 in mach_msg_trap
#1    0x9000b29c in mach_msg
#2    0x907ddad8 in __CFRunLoopRun
#3    0x907dd3dc in CFRunLoopRunSpecific
#4    0x9329bb20 in RunCurrentEventLoopInMode
#5    0x9329b1b4 in ReceiveNextEventCommon
#6    0x9329b020 in BlockUntilNextEventMatchingListInMode
#7    0x937a1bc4 in _DPSNextEvent
#8    0x937a1888 in -[NSApplication
nextEventMatchingMask:untilDate:inMode:dequeue:]
#9    0x9379ddcc in -[NSApplication run]
#10    0x9388e974 in NSApplicationMain
#11    0x00011fa8 in main at main.m:13

I don't fully understand this information but I'm assuming it represents
the normal event loop, since it looks exactly the same as when the
application runs perfectly.


John Stiles wrote:
> Is anything printed to the Run Log or Console?
>
> Dennis Hartigan-O'Connor wrote:

>> I'm trying to use a subclass of NSOutlineView to allow merged columns,
>> so that some cells can run over their bounds, using methods I read
>> about at:
>>
>> http://www.mactech.com/articles/mactech/Vol.18/18.11/1811TableTechniques/index.html
>>
>>
>> I have four instances of my custom subclass organized in an NSTabView.
>>
>> I have the rather strange problem that my program runs, without
>> crashing, and displays the tables with merged columns just as I
>> desire.  However, the main window fails to become either main or key,
>> so no input is accepted from the user.
>>
>> I've done a lot of work trying to diagnose this problem and I have two
>> key results:
>>
>> 1) Using NSOutlineViews, everything works fine.  In particular, by
>> using windowDidBecomeKey and windowDidBecomeMain methods, I find that
>> the main window becomes both key and main, and accepts user input, and
>> everything works fine.
>>
>> 2) In an attempt to diagnose this problem, I created an "empty"
>> subclass of NSOutlineView, which behaves exactly the same as
>> NSOutlineView, because no methods are overwritten.  Here's the really
>> strange part.  If I set ONE OR THREE of my four NSOutlineViews to the
>> custom "empty class", everything works fine--the application runs just
>> as if I were using four NSOutlineViews.  windowDidBecomeKey and
>> windowDidBecomeMain are both called.  If I set TWO OR FOUR of my four
>> NSOutlineViews to the custom "empty class", then the main window fails
>> to become either main or key and no input is accepted. 
>> windowDidBecomeKey and windowDidBecomeMain aren't called.
>>
>> Believe it or not, I've actually been able to make everything work by
>> adding a FIFTH instance of my custom subclass (providing merged
>> columns) to the window and setting it to be hidden.  When I do this,
>> my whole application works great, with merged columns.
>>
>> In short, my custom subclasses are somehow preventing my main window
>> from become key or main--but only when I use an even number of
>> instances of such subclasses.  When I use 1, 3, or 5 instances,
>> everything is fine.
>>
>> I am running Xcode 2.4.1 on OS 10.4.  I have already set the Nib file
>> format to "Pre-10.2", because I've heard that newer formats can cause
>> problems with custom subclasses.
>>
>> I know that this is a strange story...I hope that there is a simple
>> explanation that will make me look stupid.  My application is working,
>> but I just can't stand having to use such a blatant kludge as a hidden
>> instance of my custom subclass.
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