I think it would be good to allow the unread messages to be a part of the favorites. I have favorite file saved; they appear on the top of my list. Being able to have unread like I have on my PC allows me to navigate faster between inbox and unread. I know I can tap on the right hand corner and flag unread - just thought this option will also be a good thing to have.
Last thing, instead of having the tab on the right hand corner to toggle between unread messages etc... in the top middle shows Inbox; why not place a drop down menu there or a tap function to switch there between inbox and unread messages? Just a thought. I’m always looking for what’s convenient for me. Then again who doesn’t.