Ability to have a calendar in a separate window. Right now if you are replying to an email you need to go back and forth to see your agenda (unless you have the sidebar on or having the actual email opened in a new window). This would work the same way that it does when you double click in a conversation, opening a pop-up window separate from the main app.
Having the feature on of double-clicking on the calendar icon in the sidebar and opening it in a separate Windows, would be amazing for those like that either prefer having a full monthly view separated or working with multiple screens.
Under consideration calendar