Custom Geometry adds a button to the Firefox status bar that will resize the Firefox window to your specifications. Many other extensions will resize the window, but only to preset dimensions, such as 1024x768 or 800x600. Custom Geometry will set the window to an arbitrary size.
I needed this functionality because I prefer my browser window to be in a particular location and size on my screen. Since I'm using Microsoft Windows XP, the prospect of the browser window staying where I want it is dim. A video game, misclick, or even just a popup window (usatoday.com anyone?) will resize the window. Now, a single click gets it back into place.
If you only want this functionality to work with a particular site (for instance, your home page), then set the "Window Title" property to the title of that site or window. Using "Default" means that it works for all windows and sites.
Instructions:
1. Open the CustomGeometry-1.0.0.xpi file in Firefox 2.0.
2. Choose to install the extension.
3. Restart Firefox when instructed to do so.
4. Open the addons window by clicking "Tools," then "Add-ons."
5. Select "Custom Geometry" from the list.
6. Click the "Options" button.
7. Set the window geometry options that you prefer.
8. Hit "OK" to save your preferences.
9. Click the new icon on the lower right right side of the status bar to apply these settings at any time.