If you wanna remove swfdec-mozilla from your Debian system without removing the gnome ( as it contains the dependencies on gnome metapackage ) Then follow the following instruction :
gaurav@paliwal:~/gaurav$ sudo aptitude purge swfdec-mozilla
This will remove the swfdec-mozilla package.If you still want to keep your gnome working they run the command :
gaurav@paliwal:~/gaurav$Â sudo aptitude keep-all
This will tell Aptitude to “keep-all” installed packages. This cancels all scheduled actions on all packages (including installation, removal, or upgrade).