Wikipedia:Reference desk/Archives/Computing/2013 April 8

= April 8 =

Firefox prevent accidental quit
Because command-Q is sitting right there between command-W and command-Tab, it sometimes happens that I accidentally tell Firefox to Quit when all I really wanted to do was close a tab or a window, or switch to another app. And this is a problem, because I always have lots and lots of tabs and windows open (I'm not gonna say how many), all containing important state.

Once upon a time I had Firefox configured to warn me when I did this, but it seems to have disappeared with an upgrade somewhere along the way, and I can't find the option anywhere; now it just quits. Fortunately there's a workaround, of sorts: all I have to do is open $HOME/Library/Application Support/Firefox/Profiles/xyz.default/sessionstore.js, jump to the end of the 2 meg of JSON gobbledegook, find the string that says "state":"stopped", change "stopped" to "running", and restart Firefox, whereupon it graciously offers to restore all my tabs and windows for me. But I'd really like to find the old option, to automate or obviate this. Is there a low-level "every option ever" screen hiding somewhere, or do I need a separate plug-in for that, or what? —Steve Summit (talk) 02:51, 8 April 2013 (UTC)


 * In the location bar, go to, search for “quit”. There’s another option for altering how the session/crash restore functionality behaves, and the keyconfig extension could disable CTRL+Q altogether for you. ¦ Reisio (talk) 05:04, 8 April 2013 (UTC)


 * You can apparently change the quit key to command-shift-Q by typing defaults write NSGlobalDomain NSUserKeyEquivalents '{"Quit Firefox" = "@$Q";}' in a terminal, or use the always-ask addon (both suggestions found here, not tested). -- BenRG 05:06, 8 April 2013 (UTC)


 * I don't know why you need to go into  when there's an option for this in the preferences.  On my version of FF, it's under Preferences > Tabs > Warn me before closing multiple tabs.  Dismas |(talk) 07:50, 8 April 2013 (UTC)


 * Besides that he specifically asked for, and that its location and usage has always been more reliable than the ordinary preferences, I don’t either. ¦ Reisio (talk) 09:09, 8 April 2013 (UTC)


 * Thanks, Reisio. In about:config, browser.showQuitWarning seems to have the desired effect.  With that set to true, command-Q now pops up the dialog I had in mind, asking "Do you want Firefox to save your tabs and windows for the next time it starts?" and offering 'Quit', 'Cancel', and 'Save and Quit' buttons.


 * Dismas: I don't know why I have to go into an advanced, warranty-voiding configuration screen to achieve this functionality, either, but on this version of Firefox (5.01 on a Mac), the checkbox you mentioned under "Preferences > Tabs > Warn me before closing multiple tabs" seems only to affect the behavior when closing a window containing multiple tabs, not when quitting a session containing multiple windows or tabs. —Steve Summit (talk) 10:25, 8 April 2013 (UTC)


 * There is of course no warranty to void. :p They haven’t changed how  works in ages, so again, more reliable. ¦ Reisio (talk) 15:39, 8 April 2013 (UTC)


 * Also note that you can do History->Recently Closed Windows to get a bunch of old tabs back. --Sean 15:43, 9 April 2013 (UTC)

USB sound card
With an external USB sound card, does sound that would normally go to the 3.5mm speaker jacks go to the USB sound card? Bubba73 You talkin' to me? 03:41, 8 April 2013 (UTC)


 * If it has its own input & output, you can no doubt use those, but with the right software you should be able to use whatever audio input & output you please, too. ¦ Reisio (talk) 05:06, 8 April 2013 (UTC)

The one I'm considering has a USB input. If I play iTunes, YouTube, a website, or other sound files, the sound would normally go to the 3.5mm speaker jacks. The card should have software that would make these things go to it instead, over the USB input? Bubba73 You talkin' to me? 05:16, 8 April 2013 (UTC)

If you can link to or otherwise specify the particular device you’re talking about, a lot more could be explained more clearly. ¦ Reisio (talk) 05:26, 8 April 2013 (UTC)
 * If you mean the “card” is a USB dongle that resembles a USB stick but is an audio device instead of a storage device, without audio jacks of its own, obviously it (or rather the audio output it produces) would depend on the computer’s existing audio jacks. This is how most such things work, to my understanding. There’s no particular reason a USB device can’t work just like a PCI card. OS sees hardware, OS utilizes hardware.
 * There's no way to send analog audio over USB or PCI. PCI sound cards either have audio jacks on them or have to be separately wired to the audio jacks. -- BenRG 05:51, 8 April 2013 (UTC)


 * Ok, this card I should be able to just put it in a slot and the sound that would normally go to the speakers would go to its phono jacks, I think. But I'd rather have one like this, if it will work as I want.  It plugs into USB, has phono jack outputs and a headphone output with a volume control.  I would like for the computer sound to go to it.  Bubba73 You talkin' to me? 05:36, 8 April 2013 (UTC)


 * The USB sound card should show up as an additional audio device. Many audio players allow you to choose a non-default output device, and if not, you can set it as the default. -- BenRG 05:51, 8 April 2013 (UTC)

Thank you Bubba73 You talkin' to me? 20:21, 8 April 2013 (UTC)

How do we make a GIF?
Am I the only one around here who doesn't know how? (Particularly, the moving gifs?)

Also, what are the time-limits to how much footage can be put in a gif?

Moreover, if I decide to print it out physically, what frame will show on said print-out? (Beginning? Middle? End?) Thanks. --129.130.237.131 (talk) 04:20, 8 April 2013 (UTC)


 * It's pretty easy to create an animated GIF using GIMP -- you just have to create a multi-layer image and then save it in the right way, and each layer becomes a frame. There is no time limit in principle, but each frame increases the memory size of the GIF file.  The results of printing one depend on which print utility you use.  In most cases you just see the first frame. Looie496 (talk) 04:43, 8 April 2013 (UTC)


 * I found this it seems to be a very easy to use software. Just saying, there is no time limit but it is best not to exceed say 20 frames (but thats just my opinion). This is also because the more frames means bigger file sizes (and if your going to upload it onto a website they usually have size limits).  RunningUranium   07:11, 8 April 2013 (UTC)


 * To clarify, do you want to create animated GIFs from a utility, like GIMP, or from a program you write ? If you want help with the later, I can make some suggestions.  (See the bottom of my home page for some animated GIFs I created with my own program.)  One limitation to keep in mind is that each frame of an animated GIF can only have 256 colors.  This pretty much eliminates full color shading, but you can do 2-color shading (like red to blue). StuRat (talk) 02:52, 9 April 2013 (UTC)


 * The other two questions you asked:- No you were not the only one who doesn't know how. ;-) And for a gif displayed without a special player the first frame is the one printed or displayed if there is no animation - the format itself does not support any standard way of specifying any other frame. Dmcq (talk) 09:11, 9 April 2013 (UTC)

Terminology for error-message reduction
Many years ago, when mainframe computers became commonplace, there was a "programming paradigm" for end-user documentation to list a complete set of so-called "error messages" which were typically listed in a document explaining the meaning of each error message, often coded with an error-message id number. However, I am looking for a term that means programming in a style of "error-message reduction" where invalid data is just echoed back to the user, rather than flagged with a numbered error message. For example, in writing a span-tag:
 * Old style result: &lt;spann xx&gt; <--ERROR G45-H78P: Unrecognized keyword "spann" at line 345 column 27
 * New style result: &lt;spann xx&gt;

In the newer style of programming, it just echoes back the invalid input text, "&lt;spann xx&gt;" when an unrecognized keyword "spann" is used in the markup language, and there is no error message displayed, and no error id number, and no document to list all error messages. Sometimes that is easier, but sometimes the lack of error messages can be confusing. Question: what is that programming paradigm called, to not show a bunch of error messages, but only echo back the data, when a problem is detected? -Wikid77 (talk) 07:49, 8 April 2013 (UTC)


 * “Bad programming”. ¦ Reisio (talk) 15:42, 8 April 2013 (UTC)

Firefox crashes more unexpectedly than before
I run Firefox (latest version, it upgrades automatically) on a Windows XP computer. I have had problems for years with Firefox either crashing or freezing (and necessitating me to do a forced close through the Task Manager) when it is doing something: when I try to open a webpage with lots of content, especially scripts or media, or when I try to close one or many tabs or pages.

Lately, I have had the problem with Firefox just quitting unexpectedly without any such obvious cause (and no signs of previous distress such as slowing down) when I'm not really doing anything except reading content on an already open page. Is this something others have experienced with later versions of Firefox, or is it just that my computer is getting old or needs more memory? --Hegvald (talk) 10:21, 8 April 2013 (UTC)


 * I think it’s probably more that your computer is getting old and needs more memory (and that its OS/version is incredibly out of date and more insecure than ever). ¦ Reisio (talk) 15:41, 8 April 2013 (UTC)


 * Up until a month ago, I used to use Firefox 1.5 on an XP machine from 2006 (2 GhZ, 1 GB of RAM) for nearly all my browsing as I preferred it over later versions, with Firefox 12.0 also installed to support any pages that 1.5 didn't (e.g., HTML5). (I upgraded my machine because of increasing gaming/video speed/lag issues with my seven-year-old hardware, not anything else. And Reisio, I never had any issues with XP itself or insecurity -- only hardware issues.) I noticed that 1.5 would freeze on certain pages as well, especially ones with Javascript. I kept Javascript disabled by default, used a plugin called Keyconfig (hotkey configuring plugin) to re-enable and disable Javascript at the touch of a button for pages that needed it, and my problems disappeared. (In fact, the site that led me to do this was Wikipedia -- the internal design changed to include something that froze Firefox for ~10 seconds when loading anything, until I disabled Javascript.) -- 143.85.199.242 (talk) 16:01, 8 April 2013 (UTC)


 * Try to disable all add-ons and see what happens. Many of them are not compatible with the latest version. OsmanRF34 (talk) 16:25, 8 April 2013 (UTC)


 * I agree that something happened with Firefox (on XP) in the last month or so. It is often very slow or even freezes completely. However in past few days it caused several BSoDs! And this happened on the machine that could work for weeks without needing a restart. Ruslik_ Zero 19:20, 8 April 2013 (UTC)


 * Here's another piece of unreferenced advice for you, a little more specific than what OsmanRF34 suggested: when FF freezes, bring up Task Manager and kill the "plugin-container" task. The desired response is:
 * All flash animations crash and are replaced with a grey box,
 * Each box says "The Adobe Flash Player has crashed" or equivalent text, and
 * Firefox starts scrolling, responding, etc again.
 * If that's what happens for you, then Flash is the problem, not Firefox. Good luck -- but if this doesn't work, you're back to Osman's suggestions.
 * --DaHorsesMouth (talk) 23:35, 8 April 2013 (UTC)

Thanks all! I'll probably begin by adding some more memory to the computer and see what happens. (The computer is perhaps getting on a bit, but it's not quite as old as I may have led you to believe. It came with Vista, but I downgraded it to XP.) --Hegvald (talk) 20:39, 12 April 2013 (UTC)

Firewalls in Linux
Is there a firewall in Linux which would let me block or allow applications? (instead of port or protocols).OsmanRF34 (talk) 15:59, 8 April 2013 (UTC)


 * It looks like iptables can do it if your kernel supports the feature.
 * From the man page: "--cmd-owner name
 * Matches if the packet was created by a process with the given command name. (this option is present only if iptables was compiled under a kernel supporting this feature)" 38.111.64.107 (talk) 17:39, 8 April 2013 (UTC)

Flashing "cursor" static
I have a new ASUS computer with which I am generally impressed. But when I am on a static backgound (i.e., a white or black backgrond that is not animated or otherwise changing) I see what looks like an underline (i.e., _ ) cursor randomly flashing around the screen, appearing just long enough to be consciously visible (maybe 1/20th of a second) in black on white backgrounds, or white on dark backgrounds, maybe 5-10 times a second as I notice it. I see it now as I am typing in the edit box. I see it when I am reading the FBI/Interpol warning on copyrighted movies. I don't see it during the movie, on my desktop, or when there is some sort of moving picture like a dvd or a youtube clip playing. Can anyone suggest what this might be called, what might cause it, and where I can go for advice on how to fix it? Thanks. μηδείς (talk) 20:23, 8 April 2013 (UTC)


 * Maybe that's a dead pixel? Your guarantee should cover that. OsmanRF34 (talk) 20:28, 8 April 2013 (UTC)


 * No, it flashes all over the screen, white on dark backgrounds and black on light backgrounds, very much like analog TV static, although in the shape of _ and one at a time so far as I have noticed. μηδείς (talk) 21:14, 8 April 2013 (UTC)


 * A dancing hyphen blitting around the screen! I've worked as a graphics engineer for a long time, and although I have never seen your make-and-model system, I know exactly what symptom you're talking about.  This symptom is very frequently a characteristic of a bandwidth-starved DMA from a graphics device into a frame buffer.  That symptom will occur if the total system load is just a notch too high for the system's capabilities; and it manifests as a nearly non-deterministic data-error at very low rate.  (Therefore, the hyphen or hyphens - a few consecutive pixels in a row - appear in "totally random" locations).  It may sometimes be solved by re-calibrating or re-tuning software priorities; (this is something the manufacturer or its engineering staff will do); so as an end-user, you would need to wait for a new driver update or firmware release.  In some cases, it is a hardware performance limitation and cannot be solved through software-update.  In modern systems, it is not easy to determine when or why a DMA accelerator may become bandwidth-starved; if the root-cause were obvious or solvable through naive methods, the engineers would have already fixed it before shipping your system.  Monitor the manufacturer's website for software- and driver- updates.  Nimur (talk) 21:24, 8 April 2013 (UTC)


 * Yes, I figured this had to be some sort of processing issue, since it doesn't appear at all times. But it is a top end computer, i7 quad core 16 GB RAM, nvidia gforce gtx....  Is it possible that there's some software that I have now that I can uninstall that might help, or is it possible there's some update available now that I might look for? Thanks. μηδείς (talk) 21:41, 8 April 2013 (UTC)


 * I wonder if a different resolution (which could have a different refresh rate) would work better here. Maybe the top resolution looks good, but doesn't work for all users, so they didn't catch the problem. So, choose another resolution and see what happens. OsmanRF34 (talk) 21:38, 8 April 2013 (UTC)


 * I lowered the res to 1600/900 and the problem seems to have gotten better, but not gone away. In fact, the less frequent blinking seems more distracting, as I type! μηδείς (talk) 21:46, 8 April 2013 (UTC)


 * Checked for new drivers? []


 * I wonder if connecting to the monitor with a different type of cable might help. That is, HDMI versus D-sub, etc. StuRat (talk) 02:46, 9 April 2013 (UTC)


 * It's a laptop. μηδείς (talk) 03:08, 9 April 2013 (UTC)


 * Try an external monitor then, if only to help isolate the problem. StuRat (talk) 03:16, 9 April 2013 (UTC)
 * If it is new I'd contact the manufacturer about fixing or replacement. Dmcq (talk) 08:53, 9 April 2013 (UTC)

The 'other' Google employees
Are Google's perks for all its employees or only for a selected group of developers? Is working for Google as accountant, client manager, janitor or whatever much different than in other companies? OsmanRF34 (talk) 20:26, 8 April 2013 (UTC)


 * For all employees. But crucially many services in a typical Silicon Valley company are outsourced to contractors, whose employees thus aren't employees of that company and so don't get its benefits (they get whatever benefits their own employer has). So you'd expect security, janitorial, property-services, landscaping, and folks like that to work for some outside company that specialises in that specific task.  White-collar services like recruiting, accountancy, HR, payroll, and legal will often be split with some folks in-house and others working for another company. -- Finlay McWalterჷTalk 20:35, 8 April 2013 (UTC)