Can I disable external an monitor?

That works, excellent.

Command-F1 does exactly what I need and it does not matter whether I do it before or after I change the external monitor input source. If I do it after I have changed the input source the windows and apps that have 'disappeared' jump back to my iMac.

I cannot see a downside.

Fantastic, thank you.

So it seems my iMac does not like mirroring.

I am not sure if it is mirroring it does not like or mirroring to a monitor that is set to take its input from another source effectively ignoring my iMac. I can extend my iMac to the same monitor for hours without issue, in fact I have been doing this for months.

I found that my iMac crashed and would not restart properly until unplugged from the monitor. I found this in the Console SpinReport, it is possible this has nothing to do with the external monitor at all, it is just a coincidence?

Date/Time: 2019-11-21 08:27:45 +0000

End time: 2019-11-21 08:27:46 +0000

OS Version: Mac OS X 10.15.1 (Build 19B88)

Architecture: x86_64

Report Version: 29

Data Source: Stackshots

Shared Cache: 0x5ce9000 CBAEF121-1BF9-3B07-8ADC-A2618D70A237

Reason: (1 monitored services unresponsive): checkin with service: com.apple.WindowServer returned not alive with context: unresponsive work processor(s): WindowServer main thread 40 seconds since last successful checkin, 1 total successsful checkins since wake

Command: WindowServer

Path: /System/Library/PrivateFrameworks/SkyLight.framework/Versions/A/Resources/WindowServer

Version: ??? (???)

PID: 255

Event: service process watchdog

Duration: 0.93s

Steps: 10

Time Awake Since Boot: 60000s

Just now my iMac became unresponsive, black screen and cursor, when trying to wake it up from sleep but then it jumped into life when I unplugged the Mini DisplayPort cable from the iMac.

Any help appreciated.

Regards

Hi, I think it is a great solution, but I just wondered if anyone could tell me why my iMac seems to crash in this situation.

I plan to test further to see if I can find a workaround other than unplugging the cable.

Thank you for your help.

I felt sure there would be a script or hack I could run, after all SwitchResX can do it.

Thank you for your help.