Correct Website Button Behavior?

A button on a website typically has three states commonly referred to as 
"normal", "over", and "click".

"Normal" is what is displayed when the cursor is not positioned over the 
button.

"Over" is what is displayed when the cursor is positioned over the button
and 
the mouse is not clicked.

"Click" is what is displayed and what happens when the cursor is
positioned 
over the button and the mouse is clicked.

I've noticed that there are two common behaviors for the "click" state.
The 
first is that the appearance of the button changes upon a mouse down and
the 
action takes place upon the subsequent mouse up. The second is that the 
action takes place upon the mouse up and there is no action for the 
subsequent mouse down.

An example of the first "down/up" behavior is the Apple website which can
be 
seen at <www.apple.com>.

An example of the second "up/only" behavior is a website I'm developing  
which can be seen at <http://homepage.mac.com/taliesinsoft/ECR/>.

My query is to whether there is any agreed upon standard or convention in 
regards to button behavior. 




-- 
James Leo Ryan ..... Austin, Texas ..... taliesinsoft@[EMAIL PROTECTED]