That's what I use, but I can also second Browserstack. To be honest, no real user squishes the browser. It is arguably better to test on real devices. CSS break points are arbitrary. Embrace the squishy and hope for the best : ).

Michael 
The Web for Libraries |  www.ns4lib.com

-----Original Message-----
From: Code for Libraries [mailto:[log in to unmask]] On Behalf Of David Mayo
Sent: Thursday, January 03, 2013 11:46 AM
To: [log in to unmask]
Subject: Re: [CODE4LIB] Responsive Web Site Live

In Firefox, the Web Developer Toolbar also gives an option that animates the title with the width (and height, which is less useful) of the browser
- this can be useful for quick ballpark resize tests.

- Dave Mayo


On Thu, Jan 3, 2013 at 11:37 AM, Tom Keays <[log in to unmask]> wrote:

> Browserstack and other emulators help quite a bit in testing, and 
> testing on real devices is always advisable.
>
> But here's a nifty tool I discovered which is really useful if you are 
> just playing around with breakpoint testing on your desktop browser.
>
> http://lab.maltewassermann.com/viewport-resizer/
>
> Tom
>
> On Thu, Jan 3, 2013 at 9:15 AM, Keith Jenkins <[log in to unmask]> wrote:
>
> > Does anyone here have any experience with browser emulators such as 
> > BrowserStack?  http://www.browserstack.com/
> >
> > If so, have you come across any significant differences between the 
> > emulators and the real thing?
> >
> > Keith
> >
> >
> > On Wed, Jan 2, 2013 at 5:34 PM, Ron Gilmour <[log in to unmask]>
> wrote:
> > > Ideally, of course, one would have a mobile device lab <
> >
> http://mobile.smashingmagazine.com/2012/09/24/establishing-an-open-dev
> ice-lab/
> > >
> > > where one could test a site on all kinds of devices, but that's 
> > > not
> > likely
> > > at a small college library.
> >
>