Ok – saves all settings as modified and closes the dialog box
Cancel – discards all changes to settings and closes the dialog box
Apply – saves all settings as modified and leaves the dialog box open
Therefore, there is no reason to click Apply then immediately click Ok. Just the Ok button will suffice. Clicking Apply then Cancel is equivalent to Ok. Clicking Cancel will only discard the changes that were made since either the dialog box was opened or Apply was last clicked, whichever is most recent.
I know this is simple, but it is potentially helpful.
