Hello Xquartz users, Having now used MacOSX and Xquartz for a couple of weeks let me report about (and ask for help in dealing with) the problem of the periodical, automatic, not by the user initiated switching of fullscreen X11 to Aqua ... and back to X11 again, this all happening definitely in a less time in duration than a second. As Mr Jeremy Huddleston in a private conversation mentioned this is a known issue affecting several users and having been reported repeatedly, so I am not hesitant to pick this issue up here. :-) At first sight it seemed this phenomenon happens about once per hour, a longer observation revealed it happens at the same time *exactly* once per hour, the time-point probably depending on the moment the machine is started. A quick impression mislead this phenomenon being a Finder issue as the left pane showing mounted local and remote filesystems got visibly re-rendered at that approximate frequency. Though, this proved false (I even disconnected the ethernet cable and ran few days without a network in order to exclude remote, e.g. "nmbd"-related issues). As it seemed like a "cron"-daemon-like problem I purposefully started shutting down system processes as much as I could, please find attached the minimal process list I ended up after booting into running a usable computing environment which still includes a configuration showing this X11->Aqua->X11 phenomenon. (Being new to MacOS, not knowing any better I had to scramble Finder, Dock, Spotlight, etc *.app/ directories to keep them all off while booting ... I am very grateful to any hint how to accomplish this by some less-intrusive method, e.g. some appropriate launchd-setting or whatever is the intended method for that.) Looking at this process list there seem not very many candidates hiding the problem, and simply shooting off "UserEventAgent" I finally could reproduce this screen-switching phenomenon willfully. It appears this service is automatically started anew and during this time I always observed the screen-switching. So it appears in my case the problem is in /System/Library/UserEventPlugins/iCalAlarmAgent.plugin/ as having wiped away this directory these X11->Aqua->X11 unintended switches instantly stopped, and having closely observed the X11-behaviour for few days now since then I can confidently confirm this phenomenon is gone. Here I have to stop and humbly ask anybody with access to the appropriate source code to take a further look at the issue, I am willing to assist with experimenting by running code should this turn out helpful. :-) Greetings, Eeri Kask P.S. Process list: UID PID PPID CPU PRI NI VSZ RSS WCHAN STAT TT TIME COMMAND 0 1 0 0 31 0 600820 564 - Ss ?? 0:00.09 /sbin/launchd 0 11 1 0 31 0 600256 1292 - Ss ?? 0:00.50 /usr/libexec/kextd 0 12 1 0 31 0 79220 3240 - Ss ?? 0:00.50 /usr/sbin/DirectoryService 0 13 1 0 31 0 600236 444 - Ss ?? 0:00.03 /usr/sbin/notifyd 0 14 1 0 31 0 601332 468 - Ss ?? 0:00.12 /usr/sbin/syslogd 0 15 1 0 31 0 601812 1820 - Ss ?? 0:00.33 /usr/sbin/configd 1 16 1 0 31 0 599644 676 - Ss ?? 0:00.07 /usr/sbin/distnoted 65 17 1 0 31 0 601592 1160 - Ss ?? 0:00.03 /usr/sbin/mDNSResponder -launchd 0 21 1 0 31 0 602020 1844 - Ss ?? 0:00.08 /usr/sbin/securityd -i 213 26 1 0 31 0 77272 916 - Ss ?? 0:00.02 /System/Library/PrivateFrameworks/MobileDevice.framework/Versions/A/Resources/usbmuxd -launchd 0 27 1 0 31 0 599620 288 - Ss ?? 0:00.10 /usr/sbin/update 0 28 1 0 31 0 599660 680 - Ss ?? 0:00.01 /sbin/SystemStarter 1001 32 1 0 63 0 363496 5180 - Ss ?? 0:00.25 /System/Library/CoreServices/loginwindow.app/Contents/MacOS/loginwindow console 0 33 1 0 31 0 599736 652 - Ss ?? 0:00.00 /usr/sbin/KernelEventAgent 0 35 1 0 31 0 600184 604 - Ss ?? 0:00.01 /usr/libexec/hidd 0 36 1 0 50 0 604856 1016 - Ss ?? 0:00.02 /System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/CarbonCore.framework/Versions/A/Support/fseventsd 0 38 1 0 63 0 599664 708 - Ss ?? 0:00.01 /sbin/dynamic_pager -F /private/var/vm/swapfile 0 41 1 0 31 0 599744 940 - Ss ?? 0:00.07 /usr/sbin/diskarbitrationd 0 45 1 0 31 0 86976 2012 - Ss ?? 0:00.11 /usr/sbin/blued 0 46 1 0 31 0 599676 672 - Ss ?? 0:00.01 autofsd 0 48 1 0 31 0 75712 1664 - Ss ?? 0:00.18 /usr/libexec/ApplicationFirewall/socketfilterfw 0 53 1 0 31 0 83032 5532 - Ss ?? 0:00.46 /System/Library/CoreServices/coreservicesd 88 56 1 0 63 0 436520 31448 - Ss ?? 0:02.44 /System/Library/Frameworks/ApplicationServices.framework/Frameworks/CoreGraphics.framework/Resources/WindowServer -daemon 0 85 1 0 31 0 135500 3220 - S ?? 0:00.02 /usr/libexec/aksusbd 1001 91 1 0 31 0 599796 512 - Ss ?? 0:00.04 /sbin/launchd 1001 98 91 0 63 0 341436 2836 - S ?? 0:00.15 /usr/sbin/UserEventAgent -l Aqua 1001 100 91 0 31 0 600716 588 - S ?? 0:00.00 /usr/sbin/pboard 1001 101 91 0 47 0 431828 14368 - R ?? 0:01.97 /Applications/Utilities/Terminal.app/Contents/MacOS/Terminal -psn_0_20485 0 102 1 0 63 0 77548 1744 - Ss ?? 0:00.06 /usr/sbin/coreaudiod 1001 104 91 0 31 0 116080 2688 - S ?? 0:00.35 /System/Library/Frameworks/ApplicationServices.framework/Frameworks/ATS.framework/Support/ATSServer 1001 195 91 0 63 0 462720 19744 - S ?? 0:00.55 /Applications/Utilities/X11.app/Contents/MacOS/X11.bin -psn_0_32776 1001 229 91 0 31 0 600172 688 - S ?? 0:00.01 /bin/sh /usr/X11/bin/startx 1001 279 229 0 31 0 600908 524 - S ?? 0:00.00 /usr/X11/bin/xinit /Users/eeri/.xinitrc -- /usr/X11/bin/X :0 -auth /Users/eeri/.serverauth.229 1001 280 279 0 31 0 76392 628 - S ?? 0:00.00 /usr/X11/bin/X :0 -auth /Users/eeri/.serverauth.229 1001 378 279 0 31 0 79932 2612 - S ?? 0:00.03 xterm -geometry 80x60 0 110 101 0 31 0 76592 1128 - Ss s000 0:00.01 login -pf eeri 1001 111 110 0 31 0 600252 1148 - S s000 0:00.13 -bash 1001 379 378 0 31 0 600172 1052 - Ss+ s001 0:00.03 bash [end]