There’s a recent feature in What’s new:
You can now add multiple select options (or multiple collaborators) from the dropdown menu, without closing the dropdown menu. Just hold down Ctrl (or Cmd, for Mac users) while making your selections!
That’s nice but the implementation is confusing. When I select an option, it disappears and all I see are the options that I haven’t selected. I understand the underlying logic but it would be better if I could see what I’ve selected before I close the dropdown. Just have all the options visible, with the selected options identified somehow: bold or reverse colors, a checkbox, arrow or some other indicator.
Edited: Sorry, perhaps this should be in the Feature Requests forum.