Copy Text from Quicklook In previous versions of OS X a plist addition to com.apple.finder (outlined here for instance) could be used to enable select and copy in quicklook previews.

This (hidden) feature doesn't appear to work anymore in Mavericks. Any workarounds? Or is the setting merely named differently?
Running

defaults write -g QLEnableTextSelection -bool true


and relaunching applications works for me. defaults write com.apple.finder QLEnableTextSelection -bool true only applies to Finder but defaults write -g QLEnableTextSelection -bool true applies to all applications.

If it doesn't work, see what Quick Look generator handles plain text files:

$ qlmanage -m|grep public.plain-text
  public.plain-text -&gt; /System/Library/QuickLook/Text.qlgenerator (555.0)


If it is not Text.qlgenerator, try to delete it and run qlmanage -r.