Ooh, console tricks in Firefox's Developer tools. Greenshot, eat your heart out!
Sometimes you really need a full image of an entire webpage to show to clients and co-workers. Within Firefox right-click and open up the Developer Tools or use the standard keyboard shortcut: Ctrl-Shift-K.
Select the Console tab third item from the top in the Develop tools (using its own window).
Enter in the bottom of the console: :
screenshot --fullpage --clipboard --file --filename .png
A new .png file will be immediately downloaded to your default download location and copied to your clipboard for immediate editing in your favorite raster image editor (aka GIMP).
Here at Grip Fast Information Services and Technology we love using tools that do the job in a spectacular way and then get out of the way (and are libre/free and open source). If you'd like us to consult your workflow and optimize your processes and websites please contact us! We are your technology experts!