[xmonad] darcs patch: quick hack to avoid infinite (butbreakable) loop when...

[Klaus Weidner]

<20080517120940.GP8845 at darcs.net> <20080517181853.GD14897 at mytv> <20080518012443.GT8845 at darcs.net>
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On Sat, 17 May 2008 18:24:44 -0700, David Roundy <droundy at darcs.net> wrote:
> On Sat, May 17, 2008 at 11:18:53AM -0700, Klaus Weidner wrote:
>> On Sat, May 17, 2008 at 05:09:41AM -0700, David Roundy wrote:
>>> Probably a better option would be to not clear crossing events at all,
but
>>> instead when we handle crossing events to first check if the mouse is
still
>>> in the said window.  If it's not, then we should ignore the event.
>>
>> That sounds reasonable - how about a something like the following (not a
>> real patch - I'm still away from my computer including next week and
>> can't test this):
>>
>> XMonad/Main.hs:
>>  handle e@(CrossingEvent {ev_window = w, ev_event_type = t})
>>      | t == enterNotify && ev_mode   e == notifyNormal
>>                         && ev_detail e /= notifyInferior
>> -    = whenX (asks $ focusFollowsMouse . config) (focus w)
>> +    = whenX (asks $ focusFollowsMouse . config) $ do
>> +        dpy <- asks display
>> +        root <- asks theRoot
>> +        (_,_,w',_,_,_,_,_) <- io $ queryPointer dpy root
>> +        when (w == w') (focus w)
>>
>> XMonad/Operations.hs:
>>      mapM_ (flip setWMState withdrawnState) (W.allWindows old \\
W.allWindows ws)
>> -
>> -    unless isMouseFocused $ clearEvents enterWindowMask
> 
> Looks reasonable to me.  Of course, we'd probably also want to remove
> isMouseFocused entirely, right?

The mouseFocused functionality would still be useful for letting
updatePointer know that it's not supposed to move the pointer around. The
changes discussed won't completely fix the race conditions inherent in the
laggy X protocol, so the check that updatePointer currently does (w==w')
isn't sufficient for preventing unwanted pointer warping.

I won't have a chance to look into making or testing a patch until a week
or two from today due to being currently xmonad-less, does someone else
want to take a stab at it?

-Klaus