Disable NSTextAttachment Action and Sharing Services Menu Drop-Down
By default, NSTextView will show the NSSharingServicePicker button when you hover over an image inside the text view. That’s true even for custom image-based NSTextAttachments in the attributed string. The default menu item is limited to “Markup” and a “Services” submenu, I believe. Apps can register to be shown in this menu, and users can customize the menu in System Preferences.