Setting the paper straight

As a reminder note to myself, and for anyone else it may help, here's how you can easily set the default page size for printing in Firefox.

1. fire up firefox
2. Type about:config in the address bar
3. Confirm that you'll be careful
4. In the filter bar, type paper_size
5. Double-click the entry print.postscript.paper_size and change it's value to A4 for example
6. Hit Ok to save your modification
7. Double-click the entry print.print_paper_size and change it's value to 1 to set the value of entry print.postscript.paper_size as the default

That's it, now Firefox should have A4 as the default paper size when printing.