For all the people who asked if it is possible to stop users F5 refreshing the page. here is the solution.
case 116 : //F5
event.returnValue = false;
event.keyCode = 0;
and you have to attach the event to the function you have just created
document.onkeydown = onkeydown_handler();
i hope this will help all the seakers of the how to disable refresh button when a user clicks it.
you can allso check to see if the Ctrl/Alt/Shift key was held during the event by adding this statement
after the case.