Dictionary - With Dictionary as a part of Mac OS X (10.4 and later) there is a feature that not too many Mac users know about.
When you are in any Mac native applications you can hover your mouse above a word and press Ctrl-Cmd-D on your keyboard. You will get the Dictionary description for that word. Just move your mouse over to any other word and the Dictionary description for that word is displayed instantly.
You do not need to have the Dictionary open at all.
A few applications where this works are; Safari, Mail.app, MacJournal, TextEdit, Text Wrangler, Comic Life, iWeb, etc. Unfortunately it doesn’t work with any of the Mozilla applications, including Firefox, Camino and Flock.
Invert Screen
Another function that not too many Mac users know is Invert screen. Just press Ctrl-Option-Cmd-8 on your keyboard and see your Mac invert its colors.
Slow Motion
When you want to minimize a window, click on the yellow button in the top left corner. The window quickly goes down to the right end of your dock using either scaled or genie effect.
If you hold down the Shift key while clicking the window will minimize in a slow motion, approximately five times slower than the normal speed.
Text Clipping
If you want to save a chunk of text from the document you are viewing at the moment, for example a web page. Simply select the text, click on it and drag it to the desktop.
If you want to include the text somewhere, say in an email, you simply click the file on desktop and drag it into your composed email.
Screen Capturing
There are a few ways to capture the screen on a Mac.
You can capture the whole screen by pressing Cmd-Shift-3 on your keyboard and the screen will be captured in a PNG file and saved on your desktop as something like Picture 1.png. As of Mac OS X Snow Leopard (10.6) this file is names
You can also capture a selection, just press Cmd-Shift-4 on your keyboard and you will see a small cross hair selector on your screen.
Select the area you want to capture and let go, the file will be saved on your desktop, again something like Picture 1.png. As of Mac OS X Leopard (10.5) you also get the information on the picture size (in pixels) which changes as you move the crosshair.
You can also capture the active window. Simply follow the steps above and once you see the cross hair, press the space bar and you will get a camera icon. Hover the camera above any window and the window will get the gray overlay indicating it’s in hot-spot. You can even capture the window that is in the background, as long as a part of it visible and allows you enough room to hover the camera icon over it. Click on it and the window will be captured. The file will be placed on your desktop as Photo 1.png
However, if you’d like to capture the screen (or part of it) to the clipboard rather than to desktop, simply hold the Control key down while capturing, i.e. Shift-Ctrl-Cmd-4.
This is very handy when you need to paste the screen capture right into an email or other document.