Thanks to Griswold, I have had an opportunity to play with PyObjC, a.k.a Cocoa-Python. It is truly a fantastic way to do app development on OS X. Finding decent, "modern" code snippets for PyObjC is somewhat difficult, so I figured I'd put some up here as I stumble through interesting things. I was planning on moving the Griswold Server to a non Dock-app, so I needed to use an NSStatusBar item for it (not that I have any room left in my own menu bar). Here is some code and a sample project (yes, named "x" since I was not feeling creative) that shows how to use an NSStatusBar with an icon that changes during execution.

Everything happens in the application delegate (called "xAppDelegate" in the project). Probably not the best practice for a full app, but it makes it simple to show you an example.

from objc import YES, NO, IBOutlet, IBAction
from Foundation import *
from AppKit import *

'''
a great deal of work is done in the nib/xib file.
it has the window and button and the menu that is set as 
the status item. each menu item is wired either to a method
below or one in the first responder.
'''

class xAppDelegate(NSObject):

    statusBar = None   # holds our NSStatusBar
    mStatusMenu = None # we store our status bar menu item here
    mbImage = None     # the image that will be our initial status item
    redImage = None    # an alternate status item
    
    statusSub = objc.IBOutlet()    # the menu that will be attached to the status bar item
    prefsWindow = objc.IBOutlet()  # the mock "prefs" window
    button = objc.IBOutlet()       # button in the mock "prefs" window that will turn status item red
    
    
    # show "preferences" - called from menu item
    
    @IBAction
    def editPreferences_(self, sender):
        self.prefsWindow.makeKeyAndOrderFront_(sender)
        NSLog("Editing Preferences")

    # returns our status bar icon to the starting image
    
    @IBAction
    def makeItNormal_(self, sender):
        self.mStatusMenu.setImage_(self.mbImage)
        NSLog("making it normal")

    # turns our status bar icon to all red - called from button press
    
    @IBAction
    def makeItRed_(self, sender):
        self.mStatusMenu.setImage_(self.redImage)
        NSLog("making it normal")
        
    # when we load the nib, get the images as well

    def awakeFromNib(self):
        self.mbImage = NSImage.imageNamed_("image.jpg")
        self.redImage = NSImage.imageNamed_("red.jpg")

    # we wired up the "Quit" item in our status bar menu to "terminate:" in the first responder
    # this gets called when we really are going down
        
    def applicationWillTerminate_(self, notification):
        NSLog("We're going down")

    # when the app instantiates our class, set the menu bar
    
    def applicationDidFinishLaunching_(self, sender):

        statusBar = NSStatusBar.systemStatusBar() # grabs the system status bar

        # we may change the status bar item to a larger image, so variable length
        
        self.mStatusMenu = statusBar.statusItemWithLength_(NSVariableStatusItemLength)
        self.mStatusMenu.setImage_(self.mbImage) # set the initial image
        self.mStatusMenu.setHighlightMode_(True) # we want visual feedback when clicked
        #self.mStatusMenu.setTitle_("Status Menu") # if you uncomment this, you get a "word" menu vs image menu

        self.mStatusMenu.setMenu_(self.statusSub) # sets the menu from the NIB

The source code is commented fairly well, but upon launch, the awakeFromNib and applicationDidFinishLaunching methods will be called and you should be able to follow what is happening. As the code states, a great deal of work is done in the nib/xib file where everything is wired up:

As you can see, Interface Builder really does make life much easier.

To hide the Dock and main application menu, it is a very simple setting in the project's (and, hence, app's) Info.plist: This is just setting the LSUIElement value to "1" so the OS knows to do the hard work for us (otherwise, we need to load up the Carbon bits into Python and do it ourselves).

This code was tested in XCode 3.1 on OS X Leopard (10.5.6).