There are times when we copy some words from a webpage and find something new when we paste it, usually with some copyright related messages. See below as an example:
Test page: http://download.cnet.com/Mobogenie/3000-18511_4-75952185.html
The original source page listens to
cutevents and adds something into your clipboard.
The solution is simple:
locate dom.event.clipboardevents.enable preference item in Firefox about:config, and set it to false (default is true)
This will prevent watching behaviour towards
cut event, thus, the original pages don’t know what you have copied, or we can say: they won’t be informed when you copied something.
Here is a video showing how it works :
If you don’t want to get your hands dirty with Firefox advanced settings, you can try this add-on: