mouse pointer disappearing with some websites

How is it that some webpages have the ability to turn my mouse pointer's visibility off? It seems odd that a webpage should be able to take control of this setting. Apparently it is designed to keep people from closing a webpage quickly, either to keep an advertisement in front of that person longer or perhaps worse (ie, get the person to blindly click his mouse on a link that he doesn't realize his mouse is over because it is invisible.)

I found the solution to making the mouse reappear when this happens is to right click. But is there some setting I can choose to prevent it from happening to begin with?

thanks

Give us a few examples of web sites that turn off your mouse pointer so we can check them out. I personally have never seen that happen.