add sketch of tabbed layout.

Tabbed.hs

@@ -0,0 +1,41 @@
+module XMonadContrib.Tabbed ( tabbed ) where
+
+-- This module defines a tabbed layout.
+
+-- You can use this module with the following in your config file:
+
+-- import XMonadContrib.Tabbed
+
+-- defaultLayouts :: [Layout]
+-- defaultLayouts = [ tabbed
+--                  , ... ]
+
+import Control.Monad ( forM )
+
+import Graphics.X11.Xlib
+import XMonad
+import XMonadContrib.Decoration
+import Operations ( focus )
+
+tabbed :: Layout
+tabbed =  Layout { doLayout = dolay, modifyLayout = const (return Nothing) }
+
+dolay :: Rectangle -> [Window] -> X [(Window, Rectangle)]
+dolay sc [w] = return [(w,sc)]
+dolay sc@(Rectangle x _ wid _) ws =
+    do let ts = gentabs x wid (length ws)
+           tws = zip ts ws
+       forM tws $ \(t,w) -> newDecoration t 1 0xFF0000 0x00FFFF (trace "draw") (focus w)
+       return [ (w,shrink sc) | w <- ws ]
+
+shrink :: Rectangle -> Rectangle
+shrink (Rectangle x y w h) = Rectangle x (y+tabsize) w (h-tabsize)
+
+gentabs :: Position -> Dimension -> Int -> [Rectangle]
+gentabs _ _ 0 = []
+gentabs x1 w num = Rectangle x1 0 (wid - 2) (tabsize - 2)
+                   : gentabs (x1 + fromIntegral wid) (w - wid) (num - 1)
+                              where wid = w `div` (fromIntegral num)
+
+tabsize :: Integral a => a
+tabsize = 30