NSButton default button with blueish look

Question

I have a dialog with 1 or more buttons and want to be able to programmatically set the rightmost one be the default one, so that when the user presses the Enter or Return key it

Answer 1

The documentation says:

Note that if you set the key equivalent to Return, that button becomes the default button.

Thus, you're doing it correctly. You could try this after setting the key equivalent:

[button setNeedsDisplay:YES];

This forces the button to redraw itself.