I've been wanting Apple to add the ability to close an app or window through Exposé since I first saw Exposé. With Snow Leopard, they've at least gone part way there.

If you invoke Exposé's All Windows or App Windows mode by whatever method, you can then click on a running app in the Dock to have Exposé focus on that app (either changing focus from one app to another in App Windows mode, or switching to App Windows mode from All Windows mode).

This is nice, but better yet is that the abbreviated Dock contextual menu will show, on a single left click, allowing you to quit, hide, or set options for the focused app. The only thing missing now, IMHO, is the ability to close a specific window from Exposé, but I guess we can't have everything (yet)!

[robg adds: This only works if you click on a non-active app in the Dock while in Exposé's App Windows mode. I first tried it by clicking on the currently-displayed app's Dock icon, but that simply exits Exposé. Click on a non-active app, though, and it works as described.]

When you Shift-click the standard Sound Volume icon in the menu bar, the control that pops up changes the Alert sound volume; you can check this by opening System Preferences » Sound.

[robg adds: In prior releases of OS X, the Option key was used for this trick. However, in 10.6, the Option key is used to change the audio inputs and outputs.]

You can reveal the location of a recently-used item by holding down the Command key while looking at the Apple menu's Recent Items menu. With the Command key held down, the wording of the menu items (for Applications and Documents) changes from someitem to Show "someitem" in Finder.

[robg adds: This doesn't work in 10.5, at least not that I could figure out.]

Previously on Intel machines, zapping PRAM was limited to two restarts. Under Snow Leopard, it seems it's back to as many as you want, just like the old days.

I have been using the Screen Sharing application bundled with Mac OS X (it's in (/System/Library/CoreServices) to do all my VNC screen sharing with Windows PCs.

Since I upgraded to 10.6, every time I try to connect to a Windows PC, I just get a white screen after the password login screen.

I solved this by selecting the Screen Sharing application in the Finder, pressing Command-I, and clicking on the 'Run in 32-bit mode' checkbox. This solved all my problems; Screen Sharing now connects on the first try every time.

For those of you familiar with the old AppleScript Studio in Xcode, you may find the following information handy to know for Snow Leopard. Apple has changed quite a lot about the way things work, and you have some reading to do to get caught up.

One of the most important pieces of information from the preceding link is the part at the top of the page that reads:

AppleScriptObjC obsoletes AppleScript Studio, which is deprecated as of Mac OS X v10.6. Developers using AppleScript Studio should migrate to AppleScriptObjC, and should start new projects using AppleScriptObjC exclusively. AppleScript Studio development is still supported, but functions for creating new projects have been removed, and the AppleScript Studio palette in Interface Builder has been hidden. To re-enable it, use this command in Terminal, and then re-launch Interface Builder:

defaults write com.apple.InterfaceBuilder3 IBEnableAppleScriptStudioSupport -bool YES

Hopefully someone else finds this information as helpful as I have. Happy scripting!! :)

As we've all found, you have to turn on Text Substitutions in every app that you want to use them in. This is reminiscent of needing to do the same when Spell Checking was introduced in Cocoa. Well, to enable both by default, just paste these three lines in Terminal:

defaults write -g WebAutomaticTextReplacementEnabled -bool true
defaults write -g WebAutomaticDashSubstitutionEnabled -bool true
defaults write -g WebContinuousSpellCheckingEnabled -bool true

The first line will enable most of Text Substitutions. The second line will enable more of Text Substitutions, specifically changing '--' to '—' (em-dash). The third line will enable spell check.

Please note that these commands just set the defaults. If you have turned one of these features off in some app, then it will stay off.

After updating to Snow Leopard, I've been having issues with accidental input on my trackpad. I had forgotten where the checkbox was to disable the trackpad when I had a mouse hooked up, so I popped into the Snow Leopard help system to find the solution.

Unfortunately, there wasn't an answer there; the only thing I found discussed the "accidental input" option:

To make your trackpad inactive: Choose Apple menu > System Preferences, and then click Trackpad. Open Trackpad preferences. Select the "Ignore accidental trackpad input" checkbox to make the computer ignore the trackpad while you type.

After some digging, I discovered that the checkbox has moved to the Universal Access System Preferences panel, under the Keyboard and Mouse tab. Now if I could only find out why it was moved there.

[robg adds: On a related note, it appears the references "Ignore accidental trackpad input" checkbox is gone altogether.]

Leopard introduced the ability to use the Spotlight as a simple calculator. But, if you wanted to use exponentiation, you had to type something like pow(2, 3).

In Snow Leopard this has changed. pow no longer works, but you can instead just type 2^3, and Spotlight will display 8.

This is another notice of a change in Exposé's behavior in 10.6 -- one that I find rather annoying.

If you choose the Application Window mode (F10 by default), it (as expected) shows all the windows from the current application. But when you leave Exposé, all of these windows are left on the same "layer" they existed on prior to invoking Exposé. In 10.5, when you left All Windows mode, all of the current application's windows were brought to the front. I routinely used this feature of Exposé to achieve this particular goal.

[robg adds: I tried holding down various combinations of the modifier keys while exiting Exposé, but nothing would pull all the app's windows to the same frontmost layer.]