Monthly Archives: January 2014

how to correct the external monitor resolution

A problem that’s been bugging me since at least Mountain Lion is that sometimes when I connect my external monitor to my Macbook Pro, the display resolution is incorrect. The problem is pretty annoying as it often occurs on wake if the MBP goes to sleep even when the external monitor hasn’t been disconnected.

There are a number of solutions to this problem, and I’ve used them all. Some are less irritating than others, but in this post I’ll give you a run down of the options.

1. The old fridge magnet trick
As I often use a tiny magnet to put my MBP display to sleep while keeping the lid open, normally putting the magnet on and then taking it off again will cause the displays to reset. But this method is annoying both because I’m often connecting to external monitors away from home and because I often misplace that tiny magnet! The other problem with this method is it doesn’t always work… 😦

2. Put the external monitor to sleep with a Hot Corner
Go into System Preferences > Mission Control, and set one of the Hot Corners to ‘Put Display to Sleep’ (not ‘Start Screen Saver’). When your mac wakes up and the monitor is in the wrong resolution, move the cursor to the Hot Corner, wait a couple of seconds, and move the cursor back to the centre of the screen.

3. Activate ‘Detect Displays’
Ok, two ways to do this. The manual way is that you open System Preferences, hold down the ‘option’ key and hit the ‘Detect Displays’ button at the bottom of the window. Note that you won’t see this button unless you’re holding down the ‘option’ key. After the display resets properly, quit System Preferences. My main beef with this method is it’s totally disruptive to my workflow, so much in fact that it makes me angry every time I use it!

Fortunately, you can lower the inconvenience with the second way, which is an AppleScript that does the same thing automagically.

Update Jan 2015:
Partly in response to this problem, I’ve written an app called DisplayDroid which detects when a monitor is connected or disconnected and automatically runs a script in response. The script below is built into DisplayDroid as one of the presets that you can choose!
Find out more about DisplayDroid…

tell application "System Preferences" to quit
end try

delay 1
tell application "System Preferences"
reveal pane ""
end tell

tell application "System Events"
tell process "System Preferences"
set frontmost to true
key down option
delay 0.2
click button "Detect Displays" of window 1
delay 0.2
key up option
on error
key up option
end try
end tell
end tell

tell application "System Preferences" to quit

You might want to save this in your scripts menu or make it into a Dock-able app for convenience. Don’t forget you’ll need to allow the AppleScript editor permission to use Assistive Devices.

4. A free screen utility
Unhappy with a GUI scripting solution, I started researching how to change the displays in Cocoa or from the BASH command line so that I could avoid the overhead of System Preferences popping open and closed, which is an ugly solution at best. I didn’t get far in my research before I found that someone else had already beaten me to the punch, and had even offered the code up for free. Y’gotta love the heroes of the programming community! Download the free, which lets you change the screen resolution on any of your monitors from the status bar on your desktop. Move it from your Downloads folder into your /Applications folder. I’ve even got it in my login items for maximum convenience!


Although the app is probably slightly slower than the Hot Corner solution when I’m at home, I like it because I regularly connect my mac to all sorts of other monitors and projectors and the mac doesn’t always choose the best display. The lets you slide through the available options much more efficiently than the System Preferences panel, too. Big respect to Paul Griffin at for this!

5. Trash old prefs
No matter how well or otherwise any of these techniques work, the question remains: why is the resolution setting being forgotten in the first place? I haven’t nailed this down as a cert yet, but ever since I did this to solve a different problem, my monitor’s been behaving itself, too.

1. Go to

Hard Disk/Library/Preferences/System Configuration

Now make sure you’re at the right place because there’s another ‘System Configuration’ folder at /Library/System Configuration, and you definitely don’t want to be messing with that one. Also, this is the Library folder at the root of your hard disk and NOT your user account library (i.e, the path is /Library, not ~/Library). Check that path. Here it is again

Hard Disk/Library/Preferences/System Configuration

2. OK, click on that folder, and copy it over to your Desktop. Now go back and delete it from /Library/Preferences (or hold down ‘option’ while you drag to do a ‘move’. I prefer the first way; it’s safer, if slower).

3. Restart and test.

Hopefully, if you’ve been venting at the ears like me over the external display problem, one or more of these options will help lower the frustration!


Related Posts:
DisplayDroid from Applehelpwriter

Featured Picture: apple_display by 3DEricDesign

enable text selection in Quick Look

using quick look

One neat little feature of Quick Look is that if you want to copy some text from one pdf, rtf, or txt file (as far as I can tell, it doesn’t work with .doc and .docx) to another without opening the source file, you can browse through the Finder, hit the spacebar, and select the text from within the Quick Look preview.

However, if you find that you can’t select text inside a QL preview window, you may need to enable it in your defaults settings. To do this, triple-click the line below, copy and paste it into a Terminal window and hit ‘return’.

defaults write QLEnableTextSelection -bool true


security: keeping OS X’s nose out of your data


Over the last few years, Apple have made great strides in protecting users from losing their data, be it from system failure, software crashes, accidental deletion, disk corruption or just the plain negligence of forgetting to save before quitting. We now have Time Machine for automatic backups, application savedStates and Resume for crashes, and Autosave and Versions for negligence. As if all that wasn’t enough, iCloud is probably syncing your browser tabs, photos, and pretty much anything else you want straight up to Apple’s servers and pushing it back down the pipe to your other devices as and when needed. All this is a good thing, right?

Well, probably. For most people, most of the time. But not always. The security implications of having your OS (and even Apple) copying everything you type, open or edit on your computer can sometimes be disturbing. What if you need to open a confidential pdf in Preview but are required to make sure (either morally or contractually) that all copies of that document are destroyed after viewing? No one wants to be zeroing their hard-drive every week; and what if you need to edit a Pages or Numbers document but don’t want the changes pushed to the cloud? Turning iCloud on and off is no 2-second job and can have implications for your other workflows and data. Making duplicates to save locally risks having copies stored in the hidden .DocumentRevisions-v100 folder.

Use a secure USB
With USB flash drives now coming in at large GB sizes and relatively low cost, one solution is to load and delete sensitive files via a USB. Wiping a flash drive takes considerably less time than wiping a hard disk and keeps your sensitive data nicely partitioned from everything else, but there are problems. First, there’s always the danger of negligence; in the heat of deadlines or other pressures, we might just forget to wipe that disk; second, there’s the danger of loss or theft; and third, there’s always the possibility of deep recovery by people with the appropriate tools and know-how. Some of those issues can be mitigated by encrypting the drive using Disk Utility.

Set up a RAM disk on OS X
Using an encrypted USB can be a great idea, but it both takes time to create and is not always unobtrusive. If another party should get physical access to your USB, the fact that it’s encrypted also tells interested parties that you might have secrets to hide. A faster and less conspicuous solution could be to use a RAM disk, a portion of your RAM memory that is partitioned and formatted just like any other disk. RAM disks were once common on Macs when peripherals were considerably slower at loading data, but with the speed of modern drives few people bother with them anymore. However, a RAM disk has another advantage apart from being the fastest way to read and write data: its entirely non-persistent. There’s no way of recovering something that was once in RAM once that memory has been flushed.

A 0.5GB RAM disk

A 0.5GB RAM disk

Making, using and deleting a RAM disk is incredibly simple. Here I’ve created one that’s a half a gigabyte. To create it, you just need a one liner in Terminal. Triple-click the following line and copy and paste it directly into a Terminal window:

diskutil erasevolume HFS+ "ramdisk" `hdiutil attach -nomount ram://1165430`

After you hit ‘return’, you’ll see a new disk icon on your desktop and in the Finder sidebar. You can now use the RAM disk just like any other disk. Use it as the location to download, open or create sensitive files that you know you are going to destroy after use. You can, of course, even create copies of applications and run them from your RAM disk, too.

The RAM disk, while it exists, will behave just like any other disk, so it will have its own .Trashes directory, and its own Versions and Spotlight indexes just as all other disks do. That means you get all the comforts of OSX’s failsafes while the disk is mounted, but as soon as you eject or unmount the disk, all the Versions and Autosaves and Trashes disappear completely and unrecoverably. RAM disks are ideal for reading or editing short pieces of information (such as messages or passwords) that you want to quickly review or store before discarding without a trace.

You can eject the disk either in the usual way from within Finder or the Desktop, or you can use another Terminal line:

hdiutil detach /dev/disk1

And if you want to flush the contents of your entire RAM buffer for good measure, you can also do:

sudo purge

followed by an admin password (if you’re using any version of OS X before 10.9, you can just type ‘purge’ at the command line. No need for sudo or a password).

A word of caution, however. The strength of a RAM disk from a security point of view is simultaneously a danger from almost every other: β€” the volatility of RAM means you could easily lose everything in your RAM disk if any of the following occur: you eject the disk accidentally, the computer crashes, the power fails or battery runs flat, you log out or restart the computer. Keep these points in mind and only use your RAM disk for short sessions. Never store anything solely on a RAM disk if preserving the data is of importance to you.

Featured picture: OCD β€” security by kenns

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