title: NSTableView: programmatically adding one row results in selection of many rows with the same values?
body: <p>now, i've been reading just about everything about NSArrayController.<br>
  i have properly setup my xib, the NSArrayController, NSTableView and the bindings -- everything's working except for one odd behavior of my NSTableView.</p>
  
  <p>First some code to picture the scene:</p>
  
  <pre><code>@implementation MyAppDelegate
  
  @synthesize arrayController, dataArray;
  
  - (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
      self.dataArray = [NSMutableArray array];
  }
  
  - (IBAction)myControllerAddAction:(id)sender {
      NSString *val = [[NSDate date] description];
      NSMutableDictionary *item = [NSMutableDictionary dictionaryWithObjectsAndKeys:val, @"date", nil];
      [serversController addObject:item];
  }
  
  - (IBAction)myArrayAddAction:(id)sender {
      NSString *val = [[NSDate date] description];
      NSMutableDictionary *item = [NSMutableDictionary dictionaryWithObjectsAndKeys:val, @"date", nil];
      [[self mutableArrayValueForKey:@"dataArray"] addObject:item];
  }
  
  @end
  </code></pre>
  
  <p>using <code>-mutableArrayValueForKey:@"myNSArrayControllerStore"</code> and adding objects via the returned <code>NSMutableArray</code> proxy's <code>-addObject:myDictionary</code> the array controller instructs the table view to draw the new content but it'll <strong>select all rows with the same <em>values</em> in their <code>NSCell</code>s</strong>:</p>
  
  <p><img src="https://i.stack.imgur.com/SCFWN.png" alt="enter image description here"></p>
  
  <p>using the array controller's <code>-addObject:myDictionary</code> it'll draw the new row and select the newly added one:</p>
  
  <p><img src="https://i.stack.imgur.com/hXJED.png" alt="enter image description here"></p>
  
  <p>(on both screens i've been continuously clicking multiple times per second)</p>
  
  <p>Why is that?<br>
  Do i need to handle proper row selection on my own when using <code>[NSMutableArray -addObject:]</code>?<br>
  Or is this a bug?</p>
  
  <blockquote>
    <p>Mac OS 10.7.3<br>
    Xcode 4.3<br>
    Base SDK 10.7<br>
    Deployment target 10.6</p>
  </blockquote>