Apple is steadily adding new options to keyboard entry behaviors in OS X to provide quick access to options and to help prevent common typing mistakes. For instance, in Snow Leopard Apple introduced systemwide autocorrect to fix typos and misspelled words. With OS X Lion, Apple has brought in some additional features and behaviors, including changes to character repeats and quicker access to special characters.
In previous versions of OS X, when you pressed and held a key the system would continually enter the characters corresponding to that key until you released the key. The rate of repetition could be adjusted in the keyboard system preferences.
In OS X Lion, while the settings to adjust key repeat rate are still present, key repetition will not work with alphanumeric characters by default. If you press and hold a key to enter a number or letter, then the system will only enter one character; however, if you do the same for punctuation and other symbol characters, then the system will show the old repeating behavior as expected.
These changes were implemented in part to prevent typos, but also to make room for Apple's new special characters menu (see below). Additionally, relatively few people will need to regularly enter long strings of the same repeating alphanumeric character. Nevertheless, if you do need to enter repeats of the same character then there are some ways.
Cut and paste
An easy solution without tampering with hidden system settings is to make use of the copy and paste commands. Since pasting is not limited in the same way as character repeats, you can enter one instance of the alphanumeric character you want, then highlight it (press Shift-left arrow to do this quickly) and copy it with Command-C. Then press and hold Command-V to input the character rapidly again.
Disable repeat limitations
While the default behavior in OS X is to prevent these key repeats, you can revert this behavior permanently by issuing the following command in the Terminal, and then logging out and logging back in to your account:
defaults write -g ApplePressAndHoldEnabled -bool false
The "defaults" command is used to manage preference files (aka the Defaults system in OS X). Here we've told it to "write" and have specified the "-g" flag for the hidden global preferences file instead of specifying a program domain such as com.apple.TextEdit for Apple's TextEdit program (which would write to the com.apple.TextEdit.plist file). We've then told it to create or modify the ApplePressAndHoldEnabled setting, and change its Boolean value (yes or no, on or off, true or false) to false, thereby disabling this setting. To re-enable this setting, just repeat the command in the Terminal and replace "false" with "true."
Special characters and autocorrect
Other new features in OS X Lion relate to its autocorrect options, and include both autocorrect and the new special characters menu.
When you type text in Lion and Snow Leopard, the system will check your words against the central dictionary and automatically correct them if there is no ambiguity in the spelling. For instance, the word "teh" will be changed to "the," but the word "cand" instead of being changed will show a list of available options if you right-click it.
While this feature may be convenient, it can be frustrating to deal with at times, and for some people just having the system flag misspelled words instead of autocorrecting them may be enough. To prevent the system from autocorrecting, go to the Language & Text system preferences and uncheck "Correct Spelling Automatically" in the Text tab. In addition, you might consider disabling or modifying the entries in the symbol and text substitution list, as these will still be autocorrected even if you disable systemwide autocorrection.
In addition to autocorrection, in Lion Apple has implemented a new Special Characters feature to allow you to quickly input optional character such as those with accents for European and South American languages. In Lion, instead of a key's input repeating when it's pressed and held, you will see a small menu giving you options for the various alternative characters that are available.
The implementation of this feature is one of the reasons why Apple disabled key repeats in OS X, since holding down a character key would result in repeats instead of showing the character menu. As a result, if you use the aforementioned Terminal command to re-enable key repetition, then the special character menu will no longer work. If you need special characters and still want to have the old key repeating behavior, then you can use the character or keyboard viewers to implement them. These viewers can be enabled in the Input Sources section of the Language & Text system preferences, and then will be available in the Input Menu.
To add special characters with the keyboard viewer, use the input sources menu to display the viewer onscreen and then hold the Option key to show the keys that are associated with various accents and alternative characters. From here, pressing or clicking the respective keys will input the corresponding character, and if you need an accent then tap the accent character, release the Option key, and then tap the desired vowel or other character of choice.