Add Dock menu of unread items (like NNW had)

[Diggory]

I love the hierarchical dock menu in NetNewsWire (so much so that I'm still using v3.x)

Please implement this in Evergreen.
Thanks.

[Wevah]

Should selecting an article in the Dock menu open the article's URL (like NNW 3.x), or select the article in NNW?

[Diggory]

My personal preference is URL - but perhaps left as an option (as in NNW 3.x)

[Wevah]

"Open links in: NetNewsWire" still opens the URL (in-app insted of in-browser) vs. selecting the feed in the app, as far as I can tell. Since NNW 5 doesn't have an in-app browser yet, I'll just have it open in the default browser (which is easier than selecting the articles in the timeline, anyway).

[Wevah]

I've got this mostly working, but popping the menu is kind of slow since it has to build the entire menu when it's popped up. I may look at building the menu before it's popped, asynchronously.

Using NSMenuDelegate + menuNeedsUpdate() was fruitless, as it seems that for the Dock menu, menuNeedsUpdate() is called for the submenus right away instead of just before they're opened.

[brentsimmons]

We’re unlikely to do this — it’s a big performance hit when there are lots of unread items, which is a pretty typical thing for a lot of people.

We were able to do it in NetNewsWire of Yore because we kept all unread articles in memory all the time. We use memory better these days! But at the cost of making this feature do-able.