A module for accessing and manipulating X Window's mouse selection (the buffer used in copy and pasting). getSelection and putSelection are adaptations of Hxsel.hs and Hxput.hs from the XMonad-utils, available:

 $ darcs get <http://gorgias.mine.nu/repos/xmonad-utils>

Add import XMonad.Util.XSelection to the top of Config.hs Then make use of getSelection or promptSelection as needed; if one wanted to run Firefox with the selection as an argument (perhaps the selection string is an URL you just highlighted), then one could add to the xmonad.hs a line like thus:

 , ((modMask .|. shiftMask, xK_b), promptSelection "firefox")

There are a number of known problems with XSelection:

• Unicode handling is busted. But it's still better than calling chr to translate to ASCII, at least. As near as I can tell, the mangling happens when the String is outputted somewhere, such as via promptSelection's passing through the shell, or GHCi printing to the terminal. utf-string has IO functions which can fix this, though I do not know have to use them here. It's a complex issue; see http://www.haskell.org/pipermail/xmonad/2007-September/001967.html and http://www.haskell.org/pipermail/xmonad/2007-September/001966.html.
• Needs more elaborate functionality: Emacs' registers are nice; if you don't know what they are, see http://www.gnu.org/software/emacs/manual/html_node/emacs/Registers.html#Registers

A wrapper around getSelection. Makes it convenient to run a program with the current selection as an argument. This is convenient for handling URLs, in particular. For example, in your Config.hs you could bind a key to promptSelection "firefox"; this would allow you to highlight a URL string and then immediately open it up in Firefox.

promptSelection passes strings through the system shell, /bin/sh; if you do not wish your selected text to be interpreted or mangled by the shell, use safePromptSelection. safePromptSelection will bypass the shell using safeSpawn from XMonad.Util.Run; see its documentation for more details on the advantages and disadvantages of using safeSpawn.