I'm using Responsive Design Mode (RDM) while creating some webpages with RWD support. Usually I'm checking 3 sizes of web pages with width: 1280px/800px/360px. So on my 21:9 screen with 2560x1080px resolution, I have to put 3 windows with firefox, with 3 differen RDM sizes in them. I would be nice if I could in one tab, put few views, every one with different size settings, so I could with one refresh, see efects in three different dimensions on one screen - there is enought place, If the width would be bigger from window width, it could add a scroollbar for the view. I wanted to attach a view, how it could look, but uploading dont work :(