#MacOsX : Enable Quicklook Text Selection [OUTDATED]
Quicklook is a beautiful and powerful feature of Mac Os X (take a look here to know what is capable of) but it is somewhat weird that it doesn’t allow text selection.
To enable text selection in Quicklook:
defaults write com.apple.finder QLEnableTextSelection -boolean YES
NOTE: this trick stopped working with Mac OS X 10.11 and later.