Calling these functions during message handling results in the loss of layout state.
This fixes a number of bugs related to the combination of X.L.Minimize with a decoration.
* Added a XMonad.Util.Image module to manipulate simple images
and show them into an X drawable
* Added the possibility of using image buttons instead of plain
text buttons into the title bar
* Added a XMonad.Layout.ImageButtonDecoration as an example of
how to use the image buttons