Submission details
Multimonitor: autodetection fails after unplugging second monitor
I have a Macbook Pro and sometimes I connect an external monitor and use it as the main screen. The internal screen is disabled (booting with closed lid). When opening the lid, the internal screen stays black, but after unplugging the external screen, the internal one goes on. The problem is, that the internal screen uses the resolution of the external on.
Pressing F7/"Rotate display mode" changes from "single display" to "multimonitor". So then the internal screen has its natvie resolution, but the desktop is expanded to the external screen, which is not connected. Pressing F7 again changes back to the former state with the lower screen resolution on the internal screen.
Without using the preference pane, it's not possible to set the internal screen to its native resolution and disabling the external output. It seems that Mac OS X autodetects an newly plugged in screen, but it can't autodetec, when the screen is disconnected. So I have to manually press the button "autodetect screens" in the preference pane.
Pressing F7 on Macbook Pro should not only rotate the display mode but include the autodetection to check if the second screen is still there.
(I don't know how other Macs handle that).
Medium
Medium
Not fixed
Discussion (8 comments)
No, I completely reinstalled the system a few time during I first saw this behaviour. This only happens when the lid is closed and then the monitor is unplugged. If I open up the macbook, activate the internal screen and then unplug the external one, all works correctly. This is reproducable at any time (for me).
Btw, the F7 key should not only change between "desktop expanded" and "clone" mode but also have the option to only show the internal screen with full res.
Can you reproduce the problem on another computer?
I have only one mac. My brother has a hackintosh running, but I the external vga port doesn't work.
That's not going to be an option. Non Apple Hardware is not going to behave like Apple Hardware... The MacBook line uses Mini DVI and now Mini DisplayPort, so VGA won't be a good comparison.
I'm gonna claim this as just a quirk of the OS, perhaps this will be fixed in 10.5.8, but since you know a work-around, I'd say just use that. I don't understand why people shun the idea of using multiple displays, and getting in that habit sounds like it will resolve the issue.
Well there is no workaround. If the problem occurs, then there is only one thing you can do: press and hold the power button ...
Guy goes to the doctor and says "Doc, it hurts when I bend my arm like this"
Doctor says "Then stop doing that!"
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You said, "This only happens when the lid is closed and then the monitor is unplugged."
And my answer is to stop doing that. Leave the laptop open and learn the wonder that is two screens. Also, put the machine to sleep before disconnecting (not because it's safer, but because you're leaving that workspace).
Using two screens makes no sense in my setup, because I cannot put the two devices side by side. And turning my head 90 degrees to the left would do more hurt than it would help ... The size difference is to big as well.
I don't want to put the machine to sleep just because I want to disconnect the monitor. Btw, this sometimes causes problems too with the login box shown on the disconnected second monitor.
The solution is not to circumenvent the symptom but to cure the reason (fix the bug).
kiodane wrote on June 14, 2009, 7:59pm
Why don't you use multi monitors to begin with? I have not experienced this problem on the 4 machines I use in a similar configuration. Sounds like you may have issues that an "Archive and Install" could fix.