How to implement a toolbar button with drop down menu?

Question

The following picture is a screenshot of part of Mail app’s toolbar. The flag button is apparently an NSSegmentedCell button with a drop down menu. I want the button to have a standard action when clicked on the icon part, and a menu to drop down when the chevron is clicked. Is there a standard way to do it? I used a 2 segment NSSegmentedButton that achieves most of what I want, but I can’t get the chevron icon to show when I assign a menu to the second segment.

Edit: I could make it work if there was a system template for that chevron. Is there any other way to get it other than drawing it myself?

Answer 1

It turns out NSSegmentedControl provides setShowsMenuIndicator that draws the down chevron for a segment just like an NSPopupButton. Unfortunately, it’s only available from macOS 10.13 onwards.