Xfconf-GObject Binding -- Functions to bind Xfconf properties to GObject properties.

Note that this haskell API follows closely the original C API. Object properties should be given using their string name from the C API and not their Haskell name deriving from ReadWriteAttr.

For more information, see: http://docs.xfce.org/api/xfconf/xfconf-xfconf-binding.html

Often it may be useful to bind an Xfconf property to a GObject property. Settings dialogs often display the current value of an Xfconf property, and a user may edit the value to change the value in the Xfconf store. If the Xfconf property changes outside the settings dialog, the user will usually want to see the settings dialog automatically update to reflect the new value. With a single line of code, Xfconf's binding functionality can automate all this.

From the demo program in "Tests/Demo.hs"

 chan <- channelGet "Demo"
 --
 check0 <- checkButtonNewWithLabel "Check me !"
 label0 <- labelNew (Just "<null>")
 check1 <- checkButtonNewWithLabel "Check me !"
 --
 let xfconf_property = "/check"
     obj_property = "active"    -- toggleButtonActive attribute
 --
 -- Signals voodoo \o/
 -- * bind check buttons from/to xfconfd
 -- * thus, their "active" state will remain synchronized
 xfsig0 <- xfconfBind chan xfconf_property bool check0 obj_property
 xfsig1 <- xfconfBind chan xfconf_property bool check1 obj_property
 --
 -- * monitor xfconfd and update the label accordingly
 onPropertyChanged chan $ \key maybeValue -> do
   if key /= xfconf_property
    then return ()
    else case maybeValue of
      Just (XfconfBool True) -> labelSetText label0 "checked !"
      Just (XfconfBool False) -> labelSetText label0 "unchecked !"
      _ -> labelSetText label0 "UNKNOWN"
 --
 -- Who cares about memory management nowadays ?
 onDestroy window $ do
         mainQuit
         putStrLn "ByeBye"