Is there a way to fake a dual monitor for testing.

I have only one monitor and I have to make an application that is suitable for two monitors.

The second monitor screen should appear as a window on my primary monitor.

migrated from stackoverflow.com Oct 28 '09 at 15:59

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10 Answers 10

up vote 53 down vote accepted

I made Windows think I had two connected displays like this:

  1. Right click on the desktop, click 'Screen Resolution'
  2. Click 'Detect' on the next screen
  3. Click 'Another display not detected' and under the multiple displays option select 'Try to connect anyway on: VGA'
  4. Click 'Apply'
  5. You can now enable your desktop to be extended as if you have a second screen plugged into your computer.

To view the second screen. This can be done via LogMeIn or TeamViewer on iOS, Android, Windows, Mac and I believe Linux:

I used TeamViewer as I already use it, so already have it installed

  1. Opened TeamViewer on iPad
  2. Connect to the computer setup previously
  3. Using a 'Monitor' button at the bottom, select and show screen number 2.
  4. iPad now shows screen 2 from PC.
  • 3
    Doesn't work for me: "The display settings could not be saved. Please try a different combination of display settings." – Ray Koopa Aug 14 '14 at 17:21
  • 2
    My Win 8 didn't show 'Another display not detected' up until I installed iDisplay free windows version. Then I disable it (uncheck 'Start on windows start') and exit - it's no longer needed – Lu55 Aug 11 '15 at 12:55
  • 8
    This will work only if your graphics adapter does have a VGA port with no screen connected to it. – Vinz Sep 27 '15 at 20:53
  • 2
    How do I remove it? – Alex Jun 22 '16 at 6:01
  • 1
    A special note to windows 10: Just press Winkey+P and select Extended, windows will automatically create a second display! This is so wonderfully simple! To remove this extra one, just select back to Computer Only. @Alex – taper Dec 24 '16 at 3:13

Another free solution that works:

  • install TightVNC
  • install a virtual display driver like this or the one coming with zonescreen
  • extend the Desktop across both displays
  • start TightVNC Server
  • in TightVNC properties go to Display, Sharing area and select 'Full desktop'
  • start vncviewer and connect to localhost
  • scroll to the left/right to your virtual display and you're done

Okay, I found the solution on this site, in another question.


Since you want Windows to think there are two physical monitors, maybe Matrox PowerDesk or Virtual Display Manager would fit your needs.

  • 1
    Doesn't VDM separates a single physical monitor into multiple virtual monitors? How can you create a virtual monitor outside of the screen of the physical monitor? – Victor Marchuk Nov 14 '16 at 10:09

I found cheapest way to trick pc by physicaly making an dummy VGA (XGA,RGB) analog connector by simply putting three resistors from 50 up to 150 ohms on some connections. i have school TV setup that needed an external HDMI audio/video output as secondary monitor on windows xp system. The tricky part is that when you disconnect the main VGA monitor the whole desktop is set to the HDMI and whole secondary monitor trick just f***s up, so i made a quick search on the internet and found way to trick GPU to think that it is actual monitor connected as VGA and set that to default desktop and do not transfer desktop to the HDMI. http://www.geeks3d.com/20091230/vga-hack-how-to-make-a-vga-dummy-plug/ the resistors works as and answering mashines and if GPU sends R/G/B signals it is transfered to receiving pins and fooling the GPU that is actualy monitor on that VGA port connected. To view the desktop you can use any remote control program even the native one, and see whole desktop on dummy VGA AAAAND secondary monitor that is REAL :) Hope that will be helpful for someone. P.S. I did cut off old VGA cable connector and strip it apart, used soldering and hot glue to make sure it will not shorten the connector. The shortening of ANY connector on pc can cause malfunctions so be VERY careful and doublecheck EVERYTHING! You have beying warned ;) Good luck and sorry for any spelling mistakes i made. English isn't my language ;)

There is nothing that I know of (in order to "fake" a second monitor in software). Your only option may be to get an application that creates virtual desktops in Windows.

With that said, if this is for work, ask them to buy you one. A second monitor doesn't need to be anything fancy. There are very cheap monitors out there. If this is not for work, you may want to consider getting a second one anyway as a dual monitor setup is very useful for software developers (and in general).

  • Dell has (today, at least) a 24" 1920x1080 monitor listed (in the Home/Home Office division) for $199. There's no economic reason not to buy a second monitor for a developer. – Kyralessa Oct 28 '09 at 18:46
  • 1
    I second a second monitor. As a developer, having a dual (or even triple) monitor setup will save you insane amounts of time with debugging and research. For example, when debugging, you can have your debugger on 1 screen and the app or website you're debugging on the other and immediately see the correlation between what happens inside the app and what the user sees. And you can immediately see what the effect of HTML and CSS changes are on your website. Finally, you can easily follow video tutorials on your second screen while doing the actions they suggest on your main screen. – Nzall Jan 17 '14 at 14:55

Commercial solution ($39.95) :
If you have another computer, for example, a laptop, you can use it as second monitor by using:

MaxiVista

MaxiVista turns any spare Desktop, Laptop or Netbook PC into a dual monitor for your primary computer. No extra multi monitor hardware is required. Simply extend program windows across multiple screens as if it were one big monitor. Increase your productivity by using multiple monitors.

See this article for a detailed description:
Add multiple monitors without additional video cards using MaxiVista

image

  • 4
    ZoneScreen is a free alternative to MaxiVista : zoneos.com/zonescreen.htm – Snark Oct 29 '09 at 12:38
  • The superuser question about using a second computer as a monitor (in which both ZoneScreen and MaxiVista are covered) is here: superuser.com/questions/15254 – MatrixFrog Jan 6 '10 at 22:21
  • I tried to do this in a VM, I got a little confused until I realised that I had to disable mouse integration otherwise Windows and VirtualBox couldn't agree as to which screen the mouse was on. – Neil May 15 '14 at 23:21

Here's another solution, in theory. Once, in a support situation, I remotely operated the user's computer (don't remember right now whether it was with a Remote Desktop connection or with NetMeeting), and the user had a triple monitor setup. I saw all three of his monitors all squeezed into one window on my machine.

So, if your PC supports multiple monitors, but you don't actually have a second monitor, in theory you could exend your desktop to the 2nd monitor (even though you can't see anything, and assuming that your card supports this even when there is nothing plugged into the jack). Then you can remote into your machine from another machine to see what would be on your second monitor.

I've actually done a lot of research on this recently, because one of the products I'm working on requires a second monitor to be available for remote control of a computer -- the primary application on the computer takes over one of the monitors, so the user needs a second desktop to work on.

Both of these approaches assume you have a free video card that won't output video unless a monitor is connected:

  • If you're using an analog (VGA) monitor, then the solution is extremely easy: just put a couple resistors on the connector (one of many examples at this forum).

  • If you have a pure digital monitor (e.g. DVI-D), there's no way around it but a hardware implementation of the digital logic that needs to happen between the monitor and the PC. Sorry I have to be so vague about it.

But as others have said, you ought to just buy a second monitor (and video card if necessary). It will really be the quicker solution, and time is money, right?

By the way, whether you can take a second monitor's output and show it as a window in the first monitor would be a feature of the video card's drivers.

Try SplitView where you can split your desktop into multiple parts

  • Can you expand on that link so that your answer is still useful if it becomes dead? How do you use this particular piece of software, can you post some screenshots in your answer? – Moses Sep 23 '13 at 23:24

Simple answer: Windows 7: hit (windows button+P) extend monitor // Windows XP: Right-click/Properties/Appearance/ Under display change to desired

  • Please provide screenshots – user273580 Jun 29 '13 at 19:44
  • This solved my Windows 10 issue. Win+P > Extend > Switched my monitor cable to other port on tower. – Jonathon Aug 25 '16 at 19:12

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