title: Detecting tab view change Xcode OSX AppleScriptObjC
body: <p>I am building an application in AppleScriptObjC and I have a beginner question - how can I handle clicking on tab buttons in my app? I'm trying to make it have different sizes for each tab. I can make the window resize, but not when you click on a tab. Anyway, I've connected the tab view to the delegate
  <img src="https://i.stack.imgur.com/HwLoK.png" alt="enter image description here"></p>
  
  <p>and such, and added a <code>didSelectTabView</code> function as follows:</p>
  
  <pre><code>on didSelectTabViewItem_(tabItem)
      display alert "Testing"
  end didSelectTabViewItem_
  </code></pre>
  
  <p>...and I get the following error:</p>
  
  <pre><code>2013-05-30 18:50:10.970 MacUtil[16354:303] Error setting value for key path self of object &lt;AppDelegate @0x1005d3040: OSAID(4)&gt; (from bound object &lt;NSTabView: 0x101c05490&gt;): [&lt;AppDelegate 0x1005d3040&gt; setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key self.
  2013-05-30 18:50:10.972 MacUtil[16354:303] (
      0   CoreFoundation                      0x00007fff911210a6 __exceptionPreprocess + 198
      1   libobjc.A.dylib                     0x00007fff9522e3f0 objc_exception_throw + 43
      2   CoreFoundation                      0x00007fff91120ee8 +[NSException raise:format:arguments:] + 104
      3   AppKit                              0x00007fff92e3414c -[NSBinder _setValue:forKeyPath:ofObject:mode:validateImmediately:raisesForNotApplicableKeys:error:] + 902
      4   AppKit                              0x00007fff92e33d6d -[NSBinder setValue:forBinding:error:] + 248
      5   AppKit                              0x00007fff93493625 -[NSViewStateBinder _setValue:forBinding:errorFallbackMessage:] + 63
      6   AppKit                              0x00007fff933a5198 -[NSTabViewBinder tabView:didSelectTabViewItem:] + 330
      7   AppKit                              0x00007fff934b9c75 -[_NSBindingAdaptor tabView:didSelectTabViewItem:] + 136
      8   AppKit                              0x00007fff92fe9029 -[NSTabView selectTabViewItem:] + 1172
      9   AppKit                              0x00007fff9303ea8c -[NSTabView mouseDown:] + 156
      10  AppKit                              0x00007fff92fad60e -[NSWindow sendEvent:] + 6853
      11  AppKit                              0x00007fff92fa9744 -[NSApplication sendEvent:] + 5761
      12  AppKit                              0x00007fff92ebf2fa -[NSApplication run] + 636
      13  AppKit                              0x00007fff92e63cb6 NSApplicationMain + 869
      14  MacUtil                             0x0000000100000f0a main + 74
      15  libdyld.dylib                       0x00007fff93a297e1 start + 0
      16  ???                                 0x0000000000000003 0x0 + 3
  )
  </code></pre>
  
  <p>Any help would be appreciated!</p>