That would be up to your manufacturer, but I don't know of any that will work that way, unless there is some trick that I haven't found. __________________________________
CORNBLOSSOM

I agree with Jaime's assessment, but I have just recently got a new 7" monitor and even though it's small, it's very handy on a number of levels, and can be used as a field monitor also. Forget the lappy, get a second screen. HP Envy Phoenix/4thGen i7-4770(4@3.4GHz~turbo>3.9)
Nvidia GTX 960(4GB)/16GB DDR3/
Canon Vixia HV30/HF-M40/HF-M41/HF-G20/Olympus E-PL5.
Tape capture using 6 VCR, TBC-1000, Elite BVP4+, Sony D8 camcorder with TBC.
https://www.facebook.com/BarryAFTT

ok... thanx

Hi andrew g,
There are a number of checks you should carry out on your computer set up. James and Barry have directed you already. From my experience I would suggest you opt to:
1. Check the spec of your graphics card - physically look at the connections you have available at the back of your computer (desktop).
2. Purchase an identical monitor to the one you currently have or purchase two similar monitors that can sit alongside each other.

I have used a dual monitor set up for many years. My latest system can run 8 monitors in theory but that is definitely OTT for video editing, useful to have a third hook up for a TV display though.

Screen size is important, too small and you lose clarity of purpose, too big and it ceases to be a monitor and more a wide screen TV display. Use monitors that are fit for purpose, by this I mean they are what you need. You may be into 3D production, you need just one monitor for that and not two, the second should be 2D.

Dual monitor setups are what all editors should operate with.... makes for an enjoyable experience.

I'm not sure I go along the 7" monitor attachment route for a desktop or laptop additional screen but I know why Barry has it and I fully understand his point.

Dafydd

Footnote edit: There is one draw back to using a dual monitor setup. Using a drawing tablet. I have found a dual set up a real pain when I hook up my drawing tablet (single screen display over two monitors!).

Late edit: "two" changed to "too" - typo

Yep,
the 7" screen is a tad small, it was purchased as a field camera-monitor, but rather than have it sit in a closet when I'm not shooting, I tried it as a suite monitor, and I must say the editing experience is more fun, as the 2nd monitor can be used for my editing preview, and a place to drag assets while making decisions on editing, and works darn well as my TV screen (antenna). Gee, it took me from PD 5 to 11 to make the leap, wish I'd done it years ago.

HP Envy Phoenix/4thGen i7-4770(4@3.4GHz~turbo>3.9)
Nvidia GTX 960(4GB)/16GB DDR3/
Canon Vixia HV30/HF-M40/HF-M41/HF-G20/Olympus E-PL5.
Tape capture using 6 VCR, TBC-1000, Elite BVP4+, Sony D8 camcorder with TBC.
https://www.facebook.com/BarryAFTT

Thanx again guys. I'll have to build a bigger desk.