CVS domivogt: Try to fix fvwm using too much cpu with many PropertyNotify events.

[cvs]

CVSROOT:        /home/cvs/fvwm
Module name:    fvwm
Changes by:     domivogt        14/09/15 13:05:48

Modified files:
        fvwm           : Tag: branch-2_6 events.c events.h ewmh.c 
                         ewmh_events.c 

Log message:
Try to fix fvwm using too much cpu with many PropertyNotify events.