[xmonad] Catching exceptions from getWindowAttributes

[Adam Sjøgren]

I am trying to modify xmonad to handle exceptions thrown in
getWindowAttributes.

Since I am still copy/paste-coding, I need some help.

Take a function like this, which I have seen crashes in (especially when
using Gimp):

  floatLocation :: Window -> X (ScreenId, W.RationalRect)
  floatLocation w = withDisplay $ \d -> do
      ws <- gets windowset
      wa <- io $ getWindowAttributes d w
      let bw = (fromIntegral . wa_border_width) wa
      sc <- fromMaybe (W.current ws) <$> pointScreen (fi $ wa_x wa) (fi $ wa_y wa)

      let sr = screenRect . W.screenDetail $ sc
          rr = W.RationalRect ((fi (wa_x wa) - fi (rect_x sr)) % fi (rect_width sr))
                              ((fi (wa_y wa) - fi (rect_y sr)) % fi (rect_height sr))
                              (fi (wa_width  wa + bw*2) % fi (rect_width sr))
                              (fi (wa_height wa + bw*2) % fi (rect_height sr))

      return (W.screen sc, rr)
    where fi x = fromIntegral x

I somehow need to wrap the code from getWindowAttributes and on, in
something that "does the right thing" if gWA throws an exception.

In other places, I have done something like this:

  sendConfigureEvent :: Display -> XEventPtr -> Window -> Event -> IO ()
  sendConfigureEvent dpy ev w e = C.handle (\(C.SomeException _) -> putStrLn "sendConfigureEvent failed") $ do
                   wa <- io $ getWindowAttributes dpy w
                   setEventType ev configureNotify
                   setConfigureEvent ev w w
                       (wa_x wa) (wa_y wa) (wa_width wa)
                       (wa_height wa) (ev_border_width e) none (wa_override_redirect wa)
                   sendEvent dpy w False 0 ev

which works, but in floatLocation the type is X and not IO, and ...
well, what's a boy to do?


  Best regards,

    Adam

-- 
 "It's part of our policy not to be taken seriously"          Adam Sjøgren
                                                         asjo at koldfront.dk