I use a tiling window manager that is always changing the width of my browser window every time I open and close an application. When this happens Firefox will reflow the website that I'm looking at, causing me to lose my place in it and have to scroll up or down to find what I was looking at. Dynamic Zoom solves this problem by setting the zoom level so that the website thinks it is in a window that is always a certain number of pixels wide.
Anyone who constantly changes the width of their browser window may find this extension useful.
