I've just installed Firefox version 1.0, and have reinstalled the web developer extension.
If I chose the "resize" option on the web developer bar, the sizes I entered into the options do not show. (I've set up 800x600 and 1024x768.) I have to use "custom size" to get what I want, which is a little annoying.
I've reinstalled the extension, and I've tried deleting and re-inputting the options. Nothing.
But it works perfectly when I fill in a custom size. And everything else on the extension works. So I just have to fill in any size change as a custom one, which is not as slick as just clicking a menu option.