group.collapseAll() doesn't return a promise

[sammarland]

I have a use case where when I add a new panel to a panel group I want to collapse all panels except the newly added one. I tried to use the collapseAll() function but I can't because it doesn't return a promise which means I have a race condition. I have had to build my own array of promises from collapsing the output of the getOpen() function and then waiting for that to finish.