defaults write -g ApplePressAndHoldEnabled -bool false
Type the command to Terminal and restart the apps you would like to be affected (… or just restart the Mac altogether) to keep the characters repeating while holding its key.
Using this hack, you will also need to type the accented/alternative characters in the traditional way; which is to e.g. first press ´ then e to get é
.
To revert this hack, type defaults write -g ApplePressAndHoldEnabled -bool true
and you can use the alternative character selector once again (e.g. to get é
press and hold e until you see the selector and then choose é
from the list).
Source: In Lion, if I keep pressing a key, why doesn't it repeat?In Lion, if I keep pressing a key, why doesn't it repeat?