Replace the active app indicators in 10.5's Dock

With the release of OS X 10.5, one of the areas that received a lot of attention—most of it negative—was the new 3-D Dock. Many people, myself included, didn’t like the 3-D effects and the shadows from active windows reflecting in the Dock. Luckily, Apple included a 2-D version of the Dock that’s usually only visible when the Dock is positioned on the edge of the screen—and with a simple Terminal command, you can use this 2-D dock at the bottom of your screen as well.

One trait shared by both the 2-D and 3-D docks, though, is that the “active application” indicators—the blueish blobs below running programs—can be difficult to see when the Dock is against certain window colors or desktop backgrounds. Thankfully, it’s relatively easy to change the appearance of these indicators to something more visible. As an example, here’s a very simple modification that I did in about two minutes—not that these particular indicators are all that much more visible:

image

If you’re feeling creative and like learning new things, read on for the step-by-step directions. However, if you’d rather just have some alternate active application indicators to pick from, but you don’t want to modify the files yourself, check out LeopardDocks.com, where you’ll find a huge assortment of redone Docks. You can download any of the themes that suit your eye (look for the ones with non-standard application indicators, if that’s what you’re after), and then follow these instructions to install the replacement images in your Dock. Note that I haven’t tested this site, but it’s got the largest collection of replacement Docks that I’ve seen anywhere on the net.

So you’d like to know how to do this yourself? It’s actually pretty simple—and no Terminal required!
  1. In Finder, navigate to /System -> Library -> CoreServices, then Control-click on Dock and choose Show Package Contents from the pop-up menu. In the new window that opens, navigate to Contents -> Resources. There you’ll find the five files used to draw the active application indicators:
    • indicator_large.png, indicator_medium.png, indicator_small.png: These three are used for the 3-D dock.
    • indicator_medium_simple.png, indicator_small_simple.png: These two are used for the 2-D dock.
    Leave the Resources folder open; you’ll be using it again later.
  2. Make a backup of every file you intend to modify. To do so, simply drag the files to be modified to a folder in your user’s area, such as Documents or Desktop. Since you don’t have rights to change the source folder, OS X will make a copy instead of moving the files. (As an alternative, you could make a copy of the entire Dock application from the CoreServices folder.)
  3. Open a new window, and navigate to the spot where you just dragged the source files. Make another copy by highlighting the files and then Option-dragging them slightly (or Option-drag them to another folder entirely). You should now have two copies of each file. Keep one set as the unmodified originals, and then open the other files in Photoshop or your favorite graphic editing program (it needs to be able to handle transparent PNGs).
  4. Replace each image with something of your own design—change the blue to another color, for instance, or come up with something entirely new. I wouldn’t recommend changing the size of the original images, however.
  5. When done editing, save your modified files as PNG images with transparency.
  6. In the Finder, drag your modified images into the Resources folder you left open in step one. You’ll be asked to authenticate (but not input your password yet), and then the Finder will ask if you want to replace the original files—say yes, obviously. At this point, you’ll then be asked for your admin password; provide it, and the files should be replaced. When I tested this hint, the Finder wouldn’t replace the files even when I said yes. So instead, I deleted the originals first (authenticating when asked), then dragged in the replacements; this worked fine.
  7. Launch Disk Utility and run Repair Permissions to set the proper ownership and privileges on the files you modified.
  8. To activate your new indicators, you need to restart the Dock. Launch Activity Monitor, in Applications -> Utilities, select Dock in the list, then click the Quit Process button. A dialog will appear; click Quit in that dialog, and the Dock will restart.

If everything went according to plan, you should see your modified active application indicators in the Dock. If you don’t see them, then most likely the replace step above didn’t work—you might have to resort to my “delete first” workaround. If you ever tire of the new active app indicators, just replace your modified images with the backups you created when you started this process—or replace the entire Dock application with its backup, if you chose that route. (If you use Time Machine, you could also restore the unmodified Dock from there.) Restart the Dock again, and all should be back to normal.

To wrap this up, we need a quick aside on application signing in 10.5. Apple has digitally signed many of OS X 10.5’s applications, including the Dock, and these signed applications know when they’ve been modified. Code signing is a hacker defense; if an application has been signed and it’s been modified, the application can realize this and change its behavior. In the case of Apple’s applications, if signed applications are modified, they are locked out from the keychain. With something like Safari, this would greatly impact the program’s usefulness. The Dock, however, doesn’t access the keychain (that I’m aware of), so even if the Dock is modified, everything should still work fine.

With all that said, note that I checked the signature on the Dock after my modifications, and it still showed as signed, meaning that nothing had changed from the system’s perspective. I’m not certain of what resources are looked at by the code signing; it’s possible that image files aren’t included in the process, so changes there are fine. Whatever the reason, when I made these changes, the Dock still passed the code signature test.

You can test the signature on the Dock by using this Terminal command: codesign -dvvv /System/Library/CoreServices/Dock.app. If the program is signed, you’ll see a lot of output with details on things like file counts and authorities; if it’s not signed, you’ll just see “code object is not signed” as the only line of output. If your changes do break the Dock’s signature and you’d like to put things right again, just restore your backed-up original files to their original locations. Finally, note that I haven’t tested any of the LeopardDocks.com dock resources, so I have no idea if they will or will not break the digital signature on the Dock.

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