What's the statusbar "chain" checkbox in Konqueror?

[sam]

Hello,

I've noticed there's a box in the right corner of the statusbar in Konqueror. 
When clicked, it displays a chain link in most Styles, but in Domino it looks 
like a regular checkbox.

My empirical studies of this box have born no fruit yet. It is as compelling 
as it is mind-splitting. Does anyone happen to know what the little box does?

Thanks in advance
Sam