How to Create a Segmented NSToolbarItem like Apple Mail.app

Teaser image

Ever wondered how Apple Mail’s NSToolbar achieves the effect of individually labeled buttons shown in groups? Update 2018-11-23: I discovered a flaw in the target–action-mechanism of NSToolbarItems. They don’t fire if the label is hidden. This post’s approach is still valid enough, but is now part of a series of posts on the topic, with the 3rd one providing a fix:

Continue reading …