[xmonad] Delays in focus update...

Allen S. Rout asr at ufl.edu
Mon Feb 6 20:53:23 CET 2012

I'm running xmonad now on a 4-monitor setup which is slowly approaching 
perfect-for-me.  Yay, and thanks!

But I've noticed a certain lack of responsiveness when I make sweeping 
motions with the mouse, and I've now done a bit of an experiment  that 
seems to narrow it down.

To observe this behavior:

+ open up a lot of shells.  Mod-shift-enter 15 or 20 times on an empty 
workspace will do.

+ Pick a side of the screen which is an edge, not adjacent to another screen

+ Move your mouse to that screen, on the -opposite- side from the edge.

+ Swiftly move your mouse to the edge,  like _fast_.  10th of a second 
or so.  You're crossing many terminals.

+ Watch the successive terminals momentarily get focus;  count the time 
(seconds if you go nuts on the count) it takes for focus to get where 
your mouse is.

.... So it seems it takes constant, substantial subsecond time between 
window X gets focus, and when xmonad is willing to consider that it 
might have lost it.

Is there some timing loop in there?  Or is there something fundamental 
and X-y happening that limits this?    In other WMs, I'm accustomed to 
focus shifting nearly instantaneously, but I might be missing something.

- Allen S. Rout

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