Focus livelock

[Jukka Heinonen]

> IMO the right fix is to add support for the take focus window manager
> protocol, and avoid messing with the X focus ourselves. This is
> somewhere on my todo list...

Take focus protocol would indeed solve this problem.
According to ICCCM (and assuming Globally Active Input model)
you can only switch focus using XSetInputFocus if you either 
already have focus in one of your windows or you receive 
WM_TAKE_FOCUS client message or you receive mouse 
press/release (or passive grabbed key events, but I bet 
Wine doesn't want to deal with them).

The latter two cases also identify those places where we want
to call SetForegroundWindow (instead of in FocusIn handler) and 
if called from these two places I think livelock is not 
possible (needs to be checked).

It seems there are still few problems left:

1. DirectDraw GrabPointer forces input focus using XSetInputFocus,
   this should probably be changed to XGrabKeyboard so that we
   are compliant with ICCCM.

2. WM_TAKE_FOCUS (or mouse event) time stamp needs to be forwarded 
   to the XSetInputFocus call.

3. If WM_TAKE_FOCUS (or mouse event) handling calls 
   SetForegroundWindow, Wine application believes it has input focus 
   even though request has only been pushed into X queue.
   This means that another Wine window may still receive keyboard events,
   which could cause problems even though I fail to figure any good
   examples...

4. It is not possible for a Wine application to get input focus
   by calling SetForegroundWindow unless user clicks Wine window or
   Window Manager decides to yield focus.

5. If we have non-managed windows (by setting x11drv/Managed to N for 
   example), these windows can only get focus if they either grab keyboard
   or the application has a managed top-level window that has input focus.
   Which means clicking mouse over these windows does not transfer focus
   unless we grab keyboard (just like in case 1). However, this would mean
   that non-Wine windows stop to receive input focus...

-- 
Jukka Heinonen <http://www.iki.fi/jhei/>