Taking a screenshot bigger than the physical screen size

A screenshot is basically a copy of what is in the video buffer and what is in the buffer is what you see on the screen.

I've found a work-around (it's not perfect). Assuming this is Windows, you need to make Windows think that the screen resolution is bigger than it actually is; I used the approach as described here: http://superuser.com/questions/62051/is-there-a-way-to-fake-a-dual-second-monitor. I assume that this requires a second videocard in your computer but I'm not sure. In my case, it's the video-out of my laptop.

[quote]

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.

[/quote]

And next I took a 'standard' code for screenshots (example copied from http://stackoverflow.com/questions/15847637/take-screenshot-from-multiple-desktops-of-all-visible-applications-and-forms)

        private void button1_Click(object sender, EventArgs e)
        {
            int screenLeft   = SystemInformation.VirtualScreen.Left;
            int screenTop    = SystemInformation.VirtualScreen.Top;
            int screenWidth  = SystemInformation.VirtualScreen.Width;
            int screenHeight = SystemInformation.VirtualScreen.Height;

            using (Bitmap bmp = new Bitmap(screenWidth, screenHeight))
            {
                using (Graphics g = Graphics.FromImage(bmp))
                {
                    g.CopyFromScreen(screenLeft, screenTop, 0, 0, bmp.Size);
                }

                bmp.Save("c:\\dump.jpg", System.Drawing.Imaging.ImageFormat.Jpeg);
            }
        }

The resolution of the laptop is 1280x800; after adding the second (VGA) display, it went to 2304x800 but the VGA is only 768 heigh (so you will be missing a little there.

Disadvantage is that your mouse might move into the 'second monitor' and looks like it is gone. Also, if you're not careful, you might manage to move applications nearly completely onto the second monitor and have difficulty to drag them back.
Other disadvantage is the limitation of the VGA monitor (1024x768) so if you're running a 2048x1536 monitor, you might see a huge black area under the VGA section.

While researching, I stumbled upon http://http://virtualmonitor.github.io/. It might be worth some investigation.

Attached screenshot:
The Visual Studio window takes up the full screen of the laptop.
The browser has been moved partially onto the second monitor.