Show NSPopover from NSToolbarItem Button

Question

I want to show an NSPopover from an NSToolbarItem button in my toolbar.
(i.e. positioned below the button).

Ideally, I want to pass the

Answer 1

While I did achieve that the Popover was shown using the approach mentioned by Stuart Tevendale, I did run into problems when I tried to validate (enable / disable) the NSToolbarItems using the NSToolbarDelegate:

-(BOOL)validateToolbarItem:(NSToolbarItem *)toolbarItem {
    BOOL enable = YES;

    NSString *identifier = [toolbarItem itemIdentifier];

    // This does never get called because I am using a button inside a custom `NSToolbarItem`
    if ([identifier isEqualToString:@"Popover"]) {
        return [self someValidationMechanism];
    } 

    // For this the validation works when I am using a standard `NSToolbarItem`
    else if ([identifier isEqualToString:@"StandardToolbarItem"]){
        return [self someOtherValidationMechanism];
    }

    return enable;
}

So I would advise not to display a Popover from NSToolbarItem. An alternative might be to show a Page Sheet: How to show a NSPanel as a sheet