How to test what a webpage/web app will look like with Firefox on a specific screen resolution

Question

I have the task of testing a web application where it is given that this app should fit a screen with the resolution of 1280*1024.

My work monitor is, however, a 20 inch screen with resolution 1680*1050.

Will resizing the Firefox window to 1280*1024 meet the test criteria or should I always change the resolution of my monitor? (Obviously, the second option is not preferred).

And also: Is there a Firefox plugin which will help me to set the window size appropriately?

Answer 1

Sometimes asking the question out loud helps to realise what you really want :)

There is Firefox addon called More Display Resolutions which helps to show the page in given resolution, even in 1280*1024

After you install it, just go to Tools -> Web Developer- > Responsive Design View and here you can turn on the preffered resolution:

Ok, the above died. What now?

Since time of writing this answer I changed jobs and do not have to test specific resolutions. But I did quick google search and this site seems to be working: http://quirktools.com/screenfly/