Although, I've always preferred the Apple system of "Destructive"......"Neutral".."Constructive"
So that destructive operations are on the far left, isolated from non-destructive operations on the far right.
Yielding,
[Don't Save] [Cancel] [Save]
Also, in a window title bar (more classical than OS X now),
[Close] [Minimize/Shade] [Zoom]
Any of the buttons grouped on the left side should be considered "destructive actions", and any actions on the right side should be considered "safe" or "non-destructive actions". However, this isn't the whole story. In cases where the main, intended action is destructive, the primary action verb should still be on the right, but the [Cancel] button should be the default enabled button (what Return key does when pressed)—e.g., emptying the Trash.
So that destructive operations are on the far left, isolated from non-destructive operations on the far right.
Yielding,
Also, in a window title bar (more classical than OS X now), Any of the buttons grouped on the left side should be considered "destructive actions", and any actions on the right side should be considered "safe" or "non-destructive actions". However, this isn't the whole story. In cases where the main, intended action is destructive, the primary action verb should still be on the right, but the [Cancel] button should be the default enabled button (what Return key does when pressed)—e.g., emptying the Trash.