The apply button Windows brought to us with its windows 95 release is a strange beast.
Nearly all people I know (myself included) misuse the button.
Ask yourself: When you see the three buttons as shown on the screenshot and you want the changes you made in the dialog to take effect, what button(s) do you hit?
Chances are that you press “Apply” and then “OK”.
Which obviously is wrong.
The meaning of the buttons is as follows: “Apply” applies the changes you made, but leaves the dialog open. “Cancel” throws the changes away and closes the dialog. “OK” applies the changes and closes the dialog.
So in a situation like the above, hitting OK would suffice.
I see no real reason why the apply button is there and personally, I don’t understand why people insist on hitting it. Mind you, this also affects “educated” people: I perfectly well know how the buttons work and I’m still pressing Apply when it’s not needed.
Actually, Apply is a dangerous option set out to defeat the purpose of the Cancel-Button: Many times, I catch myself making changes and hitting “Apply” after every modification I made in the dialog, thus rendering the cancel button useless because I’m constantly applying the changes so Cancel usually will do nothing.
Why is the Apply button there then?
It’s to provide the user with feedback of her changes without forcing her to reopen the dialog.
Say you want to reconfigure the looks of your desktop. At first you change the font. Then you hit apply and you watch if you like the changes. If yes, you can now change the background and hit apply again. If not, you can manually change the font back.
Problem is that nobody uses the buttons that way and I personally have no idea why. Is it an emotional thing? Do you feel that you have to hit Apply and OK to really make it stick? I have no idea.
Personally, I prefer the Mac way of doing things: Changes you make are immediately applied, but there’s (often) a way to reset all the changes you made when you initially opened the dialog. This combines the feature of immediate response with a clean, safe way to go back to square one.
My question to you is: Do you catch yourself too doing that pointless Apply-OK-sequence? Or is it just me, many people in screencasts, my parents and many customers doing it wrongly?